Jeep will not idle under load?

Did you replace the battery with a new battery and are the terminals clean? If the voltage drops too low on this system while cranking the engine the PCM will lose the IAC step count and cause it to forget the idle position! The first thing to do is remove the air cleaner with the engine off hold the throttle wide open and look down the throttle body with a flash light. Look at the lower intake plenum gasket for leaks, oil will build up around the edges and in the corners. Has anyone tried to adjust the timing by moving the distributor? On this engine you can't, if the distributor has been turned this will throw the cam/crank sync.out! Another thing that will cause low RPM stalling is a weak/faulty CKP (crankshaft position sensor) Remember that just because the check engine light is not on does not mean that the PCM does not have any codes stored!