EGR or Vaccuum Prob?

[cryfreedom]

Well I just bought another Cherokee and it has problems staying running in idle. Basically when it's in park it will rev up to 2+ grand and stay there for about 30 seconds before it drops down to 500 rpm's. Eventually after a little bit at 500 rpm's it will die out. Also sometimes in drive it will idle down and shut itself off. As I am not an engine expert and more of "I can make that piece of metal look like a battleship" guy I am confused as to wether this could be an EGR problem or a Vaccuum problem or something completely different. And, of course, I don't want to spend money that I don't have too. A little help please! Thanks in advance.

[irocmike]

can you take a vaccum pump and use it to test your egr valve...

[Davisrats]

Take the hose off of the top of the throttle body and with it idling spray carb cleaner in the idle air controller hole, the odd shaped hole about an inch big. A replacement for the IAC is about 50 bucks.

If it idles at all it is probably not the egr (you can open it with your finger).