Pontiac Repair: 94 Grand Prix runs rough and stalls only when cold., intake manifold gasket, spped

Question
I have 94 grand prix GTP 3.4L 60k miles and when the engine is cold it starts and revs up to about 2 to 2.5k rpm.  Then it idles down to 800 and usually stalls.  It can do this sometimes about 3 times before it warms up enough then it rough idles.  Goodyear replaced computer, EGR valve and MAF sensor.  Computer has no faults stored.  Once engine warms up to about 160 it runs perfect.  Please Help!  Thanks...Cold in Buffalo

Answer
Hey Karl:

I'm just outside of Buffalo my self.

This has a vacccum leak when the engine is cold causing the excessive idle spped and surge. More than likely the lower intake manifold gasket is leaking. when the engine warms up the gasket starts to swell up and seal up again and then it runs okay. It's a pretty common issue with that engine. Good luck :}