xj man workin on a zj.
 

my parents ahve a 2004 grand cherokee wit a 4.0. and when u start it sometimes it reves up to about 3000 rpm and stays there for a few min and then finally settles back down. what can make it do this? :help:

stays there for litterally a few minutes?? what if you start driving it around right when you turn it on does it stay at 3 grand when you put it in drive??

it stays there for 2 or 3 min. and when i put it in drive and keep my foot on the brake it runs about 1800

This is a typical symptom of a bad Throttle Position Sensor (TPS)

that was kinda what i thought to. is there anyway to test a tps?

Yep go to chrysler and pay them 100bucks for the sensor and change it. if it works your good to go.
But to encourage you I would say that will fix it. I had the same issue with mine. I used to try to take off while sitting at a red light. That was kinda the last straw for me so I swapped it out. takes about 10 to change. No issues since.

they would probably charge you as much to test it.

i believe there is a way to test with a multi meter,tho i'm unsure what the readings should be.... bad IAC could also be a cause

yea thats what one of the guys i worked with said. is there a way to kno if thats bad i dont really kno much bout it.

Take it to Advance Auto Parts and have them scan the ECM for any stored codes. There's no charge.

my haynes says .20-.90 closed throttle,4.5 volts wide open