I have 01 grand cherokee, not everytime but i does often when i start the engine and rpm rise up more than 1000 rpm which i know it not normal and also sometime rpm playing going up to 2000 rpm then back to 750 rpm then go up and down over again and i hate when i put in R or D it will pop the gear because of engnie running too fast, is it thottle body cpu system or what need awnser ASAP pls cant drive that jeep like that much hate it feel that happen, HELP pls thanks

 

Forgot to add it 4.7 v8

 

do a thorough T/B cleaning above and below the butterfly, pay particular attention to the IAC passages.

 

Ok sorry what IAC?

 

Could be loose or sticking throttle position sensor.

 

IAC = Idle Air Control

 

Thanks guys for ur help!!