The throttle body gasket may develop a vacuum leak which may result in a higher than normal engine idle. Failed gaskets will require replacement.Google+
Car Problem Reports
Chevrolet 1500 Pickup Idling Problems Due to Vacuum Leak in Throttle Body Gasket
Chevrolet 1500 Pickup Problem
Engines Affected: 4.3L V6, 5.0L V8, 5.7L V8
Average Mileage: 171,000 mi (148,000 mi - 194,000 mi)
Visitor, 1994 Chevrolet 1500 Pickup, 4.3L V6, 194,000 mi
engine idles too fast, wasting fuel, and making it unsafe at slow speeds, because i have to have my foot on the brake. carb cleaner sprayed at the base of the throttle body, when idling, is sucked through, causing the enging to bog down for a short time. I suspect a gasket failure.
This problem has not been fixed yet.
Visitor, 1991 Chevrolet 1500 Pickup, 5.7L V8
I start my engine in the morning, idle goes down but in 5mins. it's back up and then shut down, after that it's hard to start and keep running,after lifting one of the injection wire to keep from flooding out, until it start,I do this for a few min. and then it may start correctly. i really don't know the real problem, but it's a serious problem now for me, now Tran don't want to back up.
Visitor, 1991 Chevrolet 1500 Pickup, 5.0L V8, 148,000 mi
higher than normal idle, just started looking for solution.