engine on 1992 GMC Vandura 2500

when engine warms up the idle gos up an down and if your setting at a stop light it will die sometimes

2 answers
Symptom: High idle. IAC counts are at 0.

System: Emissions/PCM/Fuel

Codes: N/A

Problem: TBI (Throttle Body Injector) base gasket is leaking.
belt diagram