Hesitation upon take off, engine has a rough idle

Take your distributor cap off and check for moisture. If I were a betting man, I would bet that with all the crazy rain/sleet/snow that has happened of late, you got some moisture in there and it is taking out your sparks. Dry it out, replace the cap and rotor, and see how it does.

Also look at this guide

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Please run down this guide and report back.

Also, look at the wires as well if they are older. They can look good but still leak spark when they get a bit damp. Easy way to check that is to wait until it is dark and open the hood, start the engine and look for sparks, to make it easier you can use a spray bottle and mist some plain tap water and watch for them. (do not use distilled or super filtered water, they will not work because it is the minerals in the water those processes remove that make it conductive)
If you see spark discharging replace the wires and probably the plugs if they have not been done in a while.

i have a 97 chevy C/K 1500 4x4 and it has a auto trans. it has a 5.7L vortec. Ok my question is my truck ran hot an i had a water leak an i fixed it. Now it idles rough. I though that it had a blown headgasket but it doesn't. but i can not figure out why it is running rough. could it have a burn't valve. i am having a lot of trouble and i don't want to spend a lot of money if i don't have to.

do a compression check, if any of the readings are more than twenty pounds lower could mean there is a problem with that cylinder or the valves.

https://www.2carpros.com/articles/how-to-test-engine-compression

let us know

Idles rough sometimes dies while idling mainly when the truck is warmed up have already cleared codes and cleaned up ECM ground thinking it may be a cam sensor fault but not sure it also takes a couple seconds to crank after turning the key and the motor has about 80000 miles on it

Try cleaning out the EGR valve and PCV valve and see what happens

I've done both just put a throttle position sensor on too and a new throttle body a couple weeks ago and it does have code 41 showing up which is an ignition system error

Since the problem is dealing with idle, have you checked for vacuum leaks and checked the idle air control valve (IAC)? The IAC is responsible for the engine's idle.

Yup the iac is brand new and the connector is too and I've also replaced a few vacuum lines they all look good

Have you checked vacuum at the intake?

Sure haven't ill do that and let ya know how it works appreciate it man

I'm glad to help. Between me and Rasmataz we will get you going.

When I start the engine it idles fine to begin with. I put it in gear and start driving, and by the time I get to the end of the street it has been stalling. I start it again, and it idles low and rough. When I give it the gas it hesitates badly.

I have replaced the IACV, TPS, ignition coil, cap, and rotor. A couple of months ago I rebuilt the TBI (including new fuel pressure regulator). I removed the EGR valve to examine for carbon buildup in the manifold passages beneath it and they were clear. The EGR valve itself has been replaced within the past few years. The coolant temp sensor on top of the manifold next to the water inlet is also fairly new at around six months old.

Is fuel pressure within spec? Have you checked for vacuum leaks? Any trouble codes?

The CEL came on twice during the past dozen or so times that I've driven it. On both occasions, the light reset/turned off after I turned the truck off. It is my understanding that I can't retrieve the code if the CEL has gone out. Is that correct?

I have visually inspected all the vacuum lines and can find no leaks.

Fuel pressure is something I've never checked. How can I do this?

If it is a hard code, it will stay in memory. If you can, give it a try to see if anything is showing. Also, if this happens when driving, you can use a live scanner to monitor the systems to see what is happening.

OK, just checked the code. It gave me a 44.

That is for a lean exhaust. Most likely a vacuum leak. Also, it could deal with the temp sensor or low fuel pressure.

Just checked for vacuum leaks using some spray carb cleaner. Didn't find any leaks. I also just now replaced the fuel filter.

It is still running rough and almost died when I got to the end of the street like it has been, but it might be running just a tad bit better than it was. I can't really know for sure until later on today/tonight when the temperature outside drops. Cold temperatures exacerbate the problem.

Since it is worse when it is cold outside, does that favor the problem being a bad temperature sensor vs. a bad fuel pump?

It could be either. Pumps can act funny in cold weather too.

Will be replacing the fuel pump tomorrow. I'll update this thread with results.

Before replacing it, check the pressure it is producing. It's a lot of work and money if it isn't bad.

I think I may have found the problem. I think the temp sensor connector wasn't making good electrical contact. I removed the connector and applied some dilectric grease to the contacts. (I had replaced this sensor a few months ago and did not use any dilectric grease on it at that time). When I took it for a test drive around the block it ran fine. I'm soooo glad I looked at that before I dropped the tank and replaced the pump! I'm cautiously optimistic that this has fixed the problem. We shall see....

That is good news. I hope that fixes the problem. Removing the tank is a pain.

Happy Thanksgiving,

Joe

Update: Well, my temp sensor connector theory was apparently just wishful thinking. We had a cold front blow through and the truck was running really bad in the cold weather. Since my truck has TBI, I don't have a nice handy fuel rail with a Schrader valve on it to check the pressure from. I went to the parts store to price out a fuel pressure gauge and the gauge kit I'd need that has the inline adapter costs as much as the new pump itself. So I decided to skip the gauge and just install a new pump. It wasn't really that big a deal. Took me three hours start to finish. That was totally the problem! It runs like a new truck now! I wish I had started with replacing the fuel pump instead of throwing other parts at the problem.

Thanks for your suggestions! You pointed me in the right direction.

I'm glad you got it fixed. You sound like you have the same luck as I do. (lol) I don't know where you live, but in my area, most parts stores will lend the gauge and adapter to customers with hopes to sell a new pump. Regardless, I'm glad you got it fixed.

Take care and let us know if you have questions in the future.
Joe