I have a 2004 grand cherokee limited with a power tect 4.7L V8 high output. My problem is jumping in the rpms. This ocures on or off cruse control. The rpm raises 3 to 5 then will drop back and raise again. This continues untill I stop and race the engine. The problem will then clear up for a period of time but then starts again. Thank you for any help you can give.

Curtis