Idle Speed Issues (cold start and all the time)

[AHSprite78@xxxxxxx]

Initial problem: I'd been having some problems with excessive revs at start up when the temperature starts to drop outside.  The car's probably at about 20-45 degrees F when started, then revs to about 2500rpm before gradually dropping slowly.  After about 20 seconds the engine begins to rev from 1500 to 2500 or so, just like stabbing the throttle.  Then it will drop down to normal idle (800 or so rpm) after a few revs.  

So, I was thinking it was the ICV so I used a can of carb cleaner and sprayed it down the tube connecting to the throttle body/intake boot to the ICV.  

Results: No luck.  Cold start still revs to about 2500rpm but hasn't reved up and down after 4 cold starts.  

New problem now.  The car doesn't immediatly idle at the prescribed 800rpm or so.  If the car is removed from gear and left in neutral while under way it will drop to 1000rpm, rev to 1500 and then settle in at 1000 and stay there indefinely.  When you come to a stop, same issue except if allowed to sit for 5 seconds or so it will idle at 800rpm.  Doesn't seem to matter if it's in gear, clutch in or out, brake pedal pushed.   

Anybody have any ideas on this one?

My thought was the ICV is bad so it needs replacing.  Second thought was that the throttle plate is not sealing properly.  

Not sure if this is related but under light acceleration, when shifting gears no matter how long you've been off the gas before clutching in, then engine revs once the clutch is depressed.

Thanks to all who read this and even greater thanks to those with ideas.

Matthew C Smith
'96 BMW 328is
www.rose-hulman.edu/~smithm3

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