Highter Than Nornal Idle Due to Vacuum Leak on GMC Vandura 2500

An engine vacuum leak may develop from the throttle body gasket causing a higher than normal idle speed. Failed gaskets should be replaced.

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Average mileage: 140,500 (112,000–169,000)
Engines affected: 5.7L V8, Gasoline
6 model years affected: 1990, 1991, 1992, 1993, more1994, 1995
10 people reported this problem
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problem details
1995 GMC Vandura 2500 - 5.7L V8 169,000 mi,
the van began minor irregular jerking while traveling at highway speeds as if ignition were missing in an irregular pattern. We then noticed that the engine seemed to be idling fast. Mechanic replaced the throttle barrel gasket which corrected the fast idle and the jerking seemed to be cured also,but on the first trip of some distance, the jerk began at about 30 miles out and continued to randomly occur for the 400 mile trip
It stalls when coming to a stop. Only occurs when the van is locked up. One mechanic looked and says that it is caused by air leaks in the throttlebody. Can be fixed by replacing gaskets.
1991 GMC Vandura 2500 - 5.7L V8 112,000 mi,
Hi idol bucking and stalling