Jeep Grand Cherokee Engine Idle Erratic

My Laredo Has An Rpm Of 500 To 1,000 While The Truck Is In Park? Is This Normal?

I Have Owned This Vehicle For About Eighteen Months And No Mechanic Has Been Able To Figure Out This Idle Problem. It Usually Runs High...

Now The Idle Goes Up And Down. Noticed A Cable Connection Throttle Was Off Put Thst In Its Place , Still The Up And Down With Idle. But Not...