1991 GMC Suburban erratic idle

1991 GMC SUBURBAN
209,000 MILES • V8 • 2WD • AUTOMATIC
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SHANIAC
  • MEMBER
  • 1 POST
the idle goes up and down. when i unplug the map sensor it stops idling up and down. i replaced map sensor ,problem didnt change. dont know where to start.
Oct 9, 2009 at 7:40 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,992 POSTS
Check and test the idle air control valve and throttle position sensor
Oct 9, 2009 at 11:43 PM
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