what is causing my truck to have a high idol when warm its at 1500. When I start on 1995 Chevrolet 1500 Pickup

it cold the idol is about right tell it warms up and jumps to 1500. I have changed idol control valve and throttle control valve also, but now change.

Asked by for the 1995 Chevrolet 1500 Pickup
Vacuum leak, suspect throttle body mounting gasket. Common problem on this vehicle.