Ok ive searched and nothing...maybd you guys can help. Truck starts fine run about 15-30mins idles fine no problem then I shut her off. Walk in the store come back starts right up but idle is low around 400-500 rpms. I gas it still returns to 400-500, then I take it for a drive, next stop its idling around 800-900 perfect. Problem doesnt return until I shut her off and let it sit for 5-10mins.