Engine revving upon startup

[Edgar]

Have a 94 Cutlass Supreme convertible with 3.4L that revs up high upon start up, then quickly drops almost to the point of stalling.  Just a slight touch on the pedal and it revs up again.  It will do this for several minutes before it finally smooths out to drive.  On the road, it runs fine.  No code errors showing. Have checked about every possible vacuum leak imaginable.  Makes no difference whether the engine is warm and sits overnight, the same thing happens.  Any ideas?

[19Cutlass94]

First thought would be sticking IAC. Any codes? Might wanna get a scanner and see what's going on too.

[55trucker]

as stated in the other thread....intake gaskets,....

 

if you disconnect the O2 sensor when in closed loop (engine hot)  or with a scanner force engine service mode does the problem return?

[Edgar]

Sorry for the delayed response, but the weather finally broke enough to begin tinkering with my 94 vert's engine again.  Your suggestions were right on!  The problem was the lower intake gaskets.  Replaced them and it runs like a charm.