Dodge Repair: 91 3.0L: loses power climbing a hill

Question
QUESTION: The problem I'm having is my Caravan seems like it is loosing power/not getting enough fuel when it is too warm. I have replaced the fuel filter, pump and the thermostat. The cooling system was checked and there was a coolant leak at the water pump. Replaced that pump also. The cooling fan comes on for only a few seconds (every 20-30 seconds) and idles high when it comes on. Then it drops the idle low before leveling out. Tried replacing relay and temp sensor (That is the code it gives) and that did not stop the fan from kicking on and off. When it gets warm it will die going uphill (I live at the foothills of a mountain) so this presents an issue getting home. Is this an electrical or fuel problem. My mechanic and I are really frustrated.

ANSWER: Hi Chris,
What are the present fault code numbers?
Which engine do you have (L).
When the fans come "on" what is the temp gauge showing?
When you use the AC does the fan come on and stay on?
Which relay did you replace, the fan relay?
Have you checked the egr valve as it may not be closing tightly when it needs to do so, i.e., when accelerating or slowing to a stop?

Roland

---------- FOLLOW-UP ----------

QUESTION: It is a 3.0L v6. We tried to replace the fan relay and the temp sensor. No help. I didn't ask what the number was but I will. He just said that the fault was the temp sensor. The temp gauge shows below half way. I figured that was normal but I replaced the thermostat anyway, not trusting the gauge. I can't remember if we checked the valve but I will ask that too. When I use the AC it does not stay on, it just continues doing the same thing.

Answer
Hi Chris,
Use the ignition key to get the fault codes. Turn it: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remain "on" to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat the process to be sure of an accurate set of flash counts. Then tell me the counts in order of appearance.
Let us focus on the issue of the problem when hill climbing and set aside the fan question for later.
Do check the egr valve as it might be gummed up and not closing tightly. You can spray some WD-40 on the valve stem and then move the stem back and forth to free-up the action.
Roland