92 e-350 crazy idle

My E-350 with the 5.8 v8 idles crazy.When I first start it(which in fact always starts easily), it`s fine but after it warms up the idle will cycle down and back up like it wants to stall and then it comes back and then back down again. It doesn`t do it in drive or reverse or going down the road only when in park and warmed up. could it be the TP sensor or the bypass air solinoid? on the throttle body?

Clean the IAC. Check out www.ford-trucks.com/forums That is the Ford Truck Enthuisast forum. There is a load of information on there.