When my truck warms up and im in park my idle goes up and down from 500 to 800 consitantly. can anyone help me?

 

Do you have a Haynes manual for your truck?

 

If unplugging the pre-cat oxygen sensor stabilizes the idle, replace that sensor with a dealer, NTK, or Denso part. Not Bosch, not whatever cheap crap the local discount auto parts store has, but dealer, NTK, or Denso.

If unplugging the pre-cat O2 sensor doesn't stabilize the idle, remove, clean, and reinstall the IAC (Idle Air Control, on the rear of the throttle body). If that doesn't do the trick you're probably in for a long stretch of hunting down a vacuum leak.

 

yes i do acualy haha

 

also if the precat sensor if fouled up would that also cause lack of lowend power too?

 

Then look in section #6 and test the TPS, along with all the other sensors. Also, get a TB gasket and clean it and the IAC on the back of it.