Chevrolet Repair: 1988 Silverado High Idle, fuel delivery system, throttle plate

Question
I have a 1988 Chevy Siverado CrewCab Dually with a 454. The fuel delivery system is TBI. I just bought this truck. It runs very good, but it idles at ~1100 RPM. This is on the high side, and it causes the truck to go into gear fairly hard. What could be the cause of the high idle, and what can I do to get the idle down?

Answer
Hi Arnie... check for plugged fuel system on the return side, bad TPS, throttle plate binding in the throttle body. dirty AIS. try removing the air tube to the throttle body and spray a good air inake cleaner in while running at a good rpm...also check for a vacum leak. that will cause a high idle as well...hope this helps