2002 grand 57k just started this surging at idle. Anybody have this problem? Help. I have already replaced the idle control gismo.

 

I'm no Grand expert but the experts will want to know the year and which engine you have as a bare minimum info base before the answers start flowing Dr.

 

Engine warm or cold?
Fuel pressure monitered?

 

Possible vacuum leaks, faulty fuel or electric sys., air filter clogged, fuel pump not delivering enough fuel, carburator out of adjustment, leaking head gasket, or camshaft lobes worn,. out of toubleshooting just a start. do anything to the vehical before this or let it overheat and still drive it? could be many things.

 

4.7 HO, 2002, 57.000mi, showing, no codes. On cold start up, races to 2,000+rpm, kicks down, then surges between 800 to 1500 rpm ,hot or cold, once kicked idles normally(750rpm). How's that? That's why my mech. replaced idle control module. Symptons got better but not cured

 

If the items listed above don't fix anything, then maybe you have a crankshaft sensor starting to fail, or dirty injectors...

 

Though I'm more familiar with the operation of a 97 Grand Cherokee, you may want to check the Manifold Absolute Pressure and Throttle Position sensors, both of which can cause the computer to surge the engine if they are faulty.