Now when i start my truck up it idles at 2.5k when i turn the heat on it jumps to 3k and gradually falls down. When i put it in reverse it jumps to 3-3.5k until i put it back into drive. I dunno what the hell is going on but this POS truck is pissing me off...any ideas

 

Idle Air Control valve sticking?

 

wheres that at and how can i check??

 

It is a silver valve bolted on the top of the intake manifold near the throttle body. You may have to remove a plastic cover to see it.

I don't know a good diagnostic test for it. You could remove it (2 bolts and a plug connector) and check to see if the piston is stuck open inside. Some have tried cleaning it with contact cleaner but the results seem to be mixed. It is pretty easy so I think it would be worth a try.

 

ya, that could be it.
remove the 4.0l SOHC plastic piece and its right under there.
i have taken mine off several times and cleaned the sensor with electronic parts cleaner. it seems to help it.
here is what the sensor looks like. its an older 4.0l in the pic