1995 GMC Sierra Higher than normal idle when engine is cold

1995 GMC SIERRA
114,000 MILES • V8 • 4WD • AUTOMATIC
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DASYSCYPHUS
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For the last few weeks my engine runs at a higher than normal idle speed when it's cold. It normally runs at 1000 rpm when warming up; however, lately it runs between 1300 to 1500 rpm. The SES light hasn't come on and fuel consumption is normal. The idle speed does reduce as the engine warms up, which it's supposed to do. I'm wondering if my maf valve or egr valve are possibly defective.
Feb 10, 2008 at 2:11 AM
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RASMATAZ
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I would say remove the idle air control valve and clean it and also the airbypass passages and also the throttle body/plate
Feb 10, 2008 at 3:03 AM
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SOMEGUY
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My 1988 had a throttle body injection system on a 5.7L V8. It developed this same problem. The manifold gasket on the throttle body had developed a leak. You might check that. (I put 300K+ miles on it before it sold it!)
Mar 14, 2008 at 3:18 PM
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