Engine idle

GMC C2500
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TOMHEP
  • MEMBER
  • 1 POST
I have a 1990 GMC 2500 Sierra with automatic transmission and 350 engine or 5.7 with 50,000 miles. I just replaced the engine and when I started it it will not idle but runs at about 4000 RPM's. What wrong?
Nov 17, 2007 at 9:46 AM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
Check the idle air control valve and throttle position sensor
Nov 17, 2007 at 11:41 PM
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