Engine revs?

My father in-law just had a water pump replaced by a mechanic on his van. Now there are issues(#1) with the engine operating temperature taking an unusual amount of time getting to normal. Also it is fluctuating (between norm and slightly below) while driving.(#2)Now seemingly connected to issue above, with heat on and blower working.(All fan speeds are working properly and all position selections are also) there is heated air only when engine is at higher (driving type) rpms, or in park revved to same. When rpm's are slowed only cool air is blown. Steps taken so far by him and myself are: changed radiator cap, thermostat/gasket changed. So far no change in above issues. Thank you in advance for any helpful suggestions that may be offered. Thanks again.

Hi, JOHNNY G. JR and thank you for your swift response. While awaiting an answer I found a few more posts with similar issues and they seem to agree with you. Once again I am very thankful for your help. I hope the holidays find you and yours full of happiness and joy. Thank you.

My 2002 Dodge Grand Caravan has approx. 93,500 miles on it. Recently in the last 2 months the rpms are fluctuating only when I have the ac on.
You can feel it to the point where you go forward in your seat when the rpms go down. Used to be freeway only when it happen. Now its doing it in the city. Needle just bobs back and forth unless I accelerate or put the break on. Traveling this weekend and im afraid to get on road.
Please. Any advice? Someone said an idle compensator?

I own a 2001 dodge caravan. Recently I started it and drove to the store and noticed that the rpms was running at 5000 and I was going 50 mph. So I figured the trasmission was staying in 1st gear I was told that there was a rod that needed lubed that runs into the trasmission. I dont no if thats correct or where there rod is located or what the rob is called.
I hope you can help me. And the van dont have overdrive

Ini problem, oily overflow from rediator, small bubbles in water. Replaced head gasket. Drained fluid into a ijug- it was slippery like oily and black. Turns out the thermostat was bad and only opened 10%. The jug was setting for a few days, now it is pink with no slug or oil in it. It was a bear changing the head & all belts. Now the engine starts but will not rev up correctly. Checked all connectors.

What would be the symtons if the timing belt is off by 1 tooth?

Why was the antifreeze black and slippery, but now pink with no signs of oil in it?

The check engine light operates normally. After a short drive it comes on.

How would oil an gas get into the antifreeze? I could not detect any damage to the old head gasket.

I disagree with the first reply to my original question.
I replaced a broken timing belt on a Chevette, that was assembled "off" by 1 tooth. Being off by 1 tooth alignment, the car started and would rev up ok. However, the car would only go 40 mph. I reset the itming belt by 1 tooth without the use of a timing light, because I was way out in the boonies on I70.
Then I was able to continue on my way to Ohio at the normal speed limit of 65MPH.

I was disappointed with your answere. Everything that was suggested was tried before I sent the question.

Therefore, I request my donation back. I was expecting more of a professional answere back.

02 Dodge Grand Caravan started "lurchng" with momentary rpm spikes at high speed. The engine stalled when I stopped. I let it cool down and all was ok for about 10 miles. Same thing. A mechanic rode with me with code reader and could find nothing (it didn't malfunction) during that 20 test! Afterwards, it started again. The cruise control seemed to set it off on uphill inclines as I experimented with different speeds, on/off cruise, etc. The tranny acted up as I started up, then calmed down when I pumped the accelerator a few times. Tried starting out without cruise and no problem at high speed until I set cruise on. Suddenly all was good, no problem for 100 miles. Then notices a lurch starting out from stop sign? The major problem started after passing trhough a heavy rain storm. Tranny or cruise problem? I had noticed some subtile tranny slips at startup a few weeks before this all happened.

The last transmission service (fluid and filter) was about 70,000 miles ago). Two mechanics have told me the fluid still looks good and does not smell burnt. Another mechanic recently tried "retraining" it and said it seems to work better now. I asked for a fluid and filter change but he said that would not make a difference!

The technician's advice above is very good.

I'm just a person who must maintain my own vehicles due to economic necessity (low income medical disability). Minivan transmissions seem to be notorious for problems. I believe that one of the reasons is that these newer transmissions are engineered differently, require more frequent fluid and filter changes than older transmissions and this fact is often neglected by owners. (And some mechanics) The owner's manual on my 98 Caravan SE recommends transmission service at 30,000 miles and 15,000 miles under heavy use conditions. Look up the service schedule in your manual. BE SURE TO USE THE CORRECT FLUID! The cost of replacing a transmission due to simple service neglect is too high for me to take any chances. It's inexpensive and as suggested just might help remedy your problem or help prolong the life of your transmission