Jeep Repair: eradic Idle, rpm

Question
I have a 2004 jeep grand cherokee with 4.7 HO engine. Often when idling the RPM will surge to as much as 1500 RPM then drop back to 700 RPM. It may bounce between 700 and 1500 or may idle steady between up to 1500 RPM for several minutes. What can I do to correct this?

Answer
That could also be because other things in your motor are turning on and off and they requre mroe motor power to run those things. aka. if your a/c cuts on your RPMs will go up. when it cuts off the RPMs will drop. Does this make sence or is it very eradic like 700 - 1500- 700 -1500- 700 within a few sec.