I have a 2000 Durango with the 4.7L engine. Whenever the engine is idling in park, the engine RPM's jump up and down from 700 RPM where it usually sits in park and 1500 RPM's. I can usually get it to calm down if I rev it up and let it come down to normal. I don't notice the porblem while driving. What would cause this? I assume there is a sensor about to go somewhere, but I have no idea which one. Any help would be greatly appreciated.

 

sounds like a TPS (throttle position sensor) it's on the throttle body (grey) closest to the fire wall. they run $30 at your local parts store. hope that helps

rock