What would cause my 99 Cherokee to idle between 1000 and 2000rpm???

 

Vacuum leak or IAC failure. To check the IAC take the intake hose off and cover the bypass port with your thumb the engine should stall. If it does not stall cover the throttle body with the palm of your hand. It should stall. If both of these tests don't stall the engine check every hose coming off of the intake manifold.

 

Is this a good way to check if you have vacuum leaks or will this not test the whole system? I haven't found a vacuum diagram so I don't know if all the vacuum lines end up going to the intake at some point.

If anyone has a diagram post it up please, it would be much appreciated.

 

All vacuum lines start at the intake then branch out. A small tiny vacuum leak most likely won't allow the engine to run if it were on one of the thin pipes.