Engine poor performance

Oil is leaking from the seal and is getting into the cylinders making it hard for them to fire properly. That is the smoke from the exhaust, burnt oil. Replacing the seals should fix the problem. The mileage is low for this to happen if it is 10300 and not a typo.

Okay. First, the fact that the engine stalled when spraying carb cleaner in it is normal. I just wondered where you sprayed it. If it was around the IMRC seals then you have a quite large vacuum leak. The IMRC runs from the intake manifold just behind the throttle body to the head giving clyinders extra or or a longer intake port which gives you low end torque and high RPM horsepower. There are 2 signals that actuate the electrical box that opens the butterfly valve in the IMRC. A spring ussually keeps it closed, but when the throttle posistion sensor, TPS and the crank positon sensor, CKP indicate a positive increase in the throttle position and an increase in RPMs, the butterfly opens to increase performance at higher RPMs. Depending on the engine this happens at either 1500 or 3000 RPM.
So, if you are having a rough idle issue, then there is a vaccum leak at the IMRC seal and the seal needs to be replaced. If the seal does not seem to leak vacuum, you will hear a hissing sound of air being sucked in or use a piece of thread to see if it gets sucked towards the seal area, then the butterfly valve may be stuck open which would create a rough idle and performance issues form 1500-3000 RPM and even above as the signal to the PCM which goes to the ECU will be incorrect and other parameters such as air/fuel curves and ignition curves may be affected by the inaccurate signal information.
If oil is leaking from the seal at the head or it seems to have a vacuum leak, it needs to be replaced.
You may have to check the TPS and CKP for functionality as they could also be giving a false signal to the PCM and opening the valve to early too late or keeping it open or closed at all times.
Check the IMRC butterfly valve by identifying the butterfly arm that the linkage or cable actuates, depending on engine, to check it for smooth operation and the resistance from the spring that keeps the valve closed. I included a diagram of the system to idntify the components.
If all of this seems to be in order, you may have to check the port for the IMRC just behind the throttle body for carbon build up. If you find any deposits, even in the throttle body, clean it with carb cleaner but make sure you spray out ports from the inside out towards the intake manifold. This prevents deposits from moving further into the IMRC port and will hopefully push them out as they tend to build up near the intake manifold. On the other end you may have deposits at the cylinder head. Cleaning it is the same but spray towards the cylinder head as to prevent the same thing as deposits build up near cylinder.
That is all the mechanical check s you can do besides checking for a vacuum leak elsewhere on the engine.
Otherwise you should have the trouble codes pulled. Any Advance Auto or Auto Zone will do this for free. The code will give a brief description of the faulty component.
That is about all the advice I can give you. If you get a trouble code that you need help with or have any questions, please reply to post again and I will be glad to help you out ASAP.

I looked up the trouble codes and they are a lean/rich or fuel and or air control problem. It associates it with air and/or vacuum leaks and obstructions in the air tract. So, make sure that the butterfly valve is not sticking shut. I realize that is hard to do without the special test connector. There may be a way to use a multi-meter. So, after you repair the leaks if you still have any issues you can come back and I will try to figure out if there is a way to do a coninuity test. I really doubt it though as the system requires voltage signals and you don't want to risk shorting out the connector.
Since you sprayed the carb cleaner at the seals and both seals made the engine stall, I wonder if the valve is stuck open. I say this because the valve should be closed and cleaner should not get in unless it gets by the seals and makes it into the tract via the intake manifold. If the seals are really bad, this is a definate possiblity.
As far as replacing the gaskets I would replace both upper and lower as you are already in there and if you shuffle enough stuff around you may break the seal for the lower manifold just by working around it. So, yes, I would do both. It certainly won't hurt and if it leaks later you will wonder if it is an issue if you have performance problems in the near or distant future. It is not a lot more work to get to them either.
Make sure the butterfly moves freely and check for carbon deposits when you have it apart. You may want to run some good fuel system cleaner such as SEA FOAM or BG44K. They are really the only2 that work. After the second can deposits will still be floating around and it may take another tank to see the true results of using the cleaner. Be prepared to change your oil as the cleaners work so well at removing deposits which end up in the oil, it needs to be changed after using it.
Good luck and let me know how things go.

You r very welcome and definately let me know how things go. We are always here if you need any advice or have another problem in the future. We have a really good team of Techs.
Merry Christmas and a Happy New Year to you too!

Take care.

Dr. C

Usually the catytic converter burns red hot from too much gas or if has collapsed in on itself and is clogging the exhause tract.
Run a test light on the #4 injector to see if it is firing. Even if it is not it would not cause this issue.
Check for an exhaust leak the O2 sensor which would cause it to think it is running lean and dump a bunch of gas into the engine. Also, the O2 sensor near the catytic converter may be bad.
I really think with the performance issues you have, the mileage and the age of the van that the catytic converter collapsing in on itself is the most likely scenario. Take a rubber mallet or your hand and bang on it. See if it sounds like it is full of loose stuff. If it is red hot and sounds like it is loose inside, that is probably the issue. If you had a vacuum leak that were causing the issue, you would hear it or it might hang in idle sometime.
You can get a chain type pipe cutter on a loaner basis at Advance Atuo or Auto Zone. It is pretty easy to cut out the old one, get an new one that is the proper inner diameter or outer diameter, depending on whether you clamp it inside our outside. Clamping the converter to the outside is best so the pipe would slip inside where you cut it then clamp it with exhaust clamps. You may need to get exhaust step downs or extensions, but replacing a cat is no too bad. Make sure it meets EPA Hydrocarbon standards. If you get one for your truck or ask for a universal for the size of your engine, you should be fine.
I really think that is the problem if it is red hot. After you check the injector, if it is firing run a can or 2 of fuel system cleaner. Sea foam or BGT 44K are the only 2 that do any good. You may have to change the oil after you use them as they cklean out so much stuff. It make take a third tank of gas for all the deposits that may be clogging the injector to come loose, so wait until you run a tank withouot cleaner to evaluate performance and change oil.
Let me knwo how it goes.

Your very welcome. I appreciate the thanks as that is what we rally work for here, helping people through situations and having them be happy with the results. I hope it goes well and we will be here in case you run into any problems along the way.

Dr. C

You are very welcome. God works through all of us, so the tahanks ultimately goes to him. If it wasn't for Christ to give us our lord. Where would we be.
A thanks is worth a lot as not many people do that. It really goes a long way with me. I do this job, and most of the other Techs and it is the founding beliefs of upper management and the owners that, helping people, other peole in general, is the most important thing. It is a great feeling when I get a response like this where a plan comes together and the vehicle gets fixed not only for free, but I bet you did a better job than most techs as they are in a race with, "The Clock" to make up for when they get a job where they lose time.
Don't you feel great having fixed your own truck? You can keep it maintained and do maintenance repairs and get a lot more time out of it. Labor is the most costly part of repairs. Some shops are nearing, of course dealerships already have, the $100/hour mark.
Not that they don't deserve it as they have to know every manufacturer and every model and keep up with all the new technology. When they break a bolt, it can be devastating to a paycheck. So, they tend to rush through other jobs in case that happens.
We are all here to help each other and when you come back again, I think you will find that same attitude in anyone you deal with.

Take care and God Bless.

Dr. C