I have a 89 formula 350 the problem is the damn thing never has a smooth idle . When you sit in park the rpm will rum up 200 rpm and back down in never ending secession . i have herd of this from fellow owners of 3 geners but no one has a clue what it is ,do you?
Sounds like a vacuum leak.. If not that, then you've got a bad IAC. Those are the best two possibilities without any better description.
-Bruce
IAC, probably just dirty. Spray it with Carb Cleaner, usually fixes this very common issue. Vacuum leaks would cause other issues aside from varying idle.
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98 Camaro
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