Michael,
How cold was it when you started the car? Was the cold control pressure within spec for that temperature?
There is a procedure for testing the Aux Air Valve. It's located on the side of the engine and is fairly easy to get to. It's item #36 in this diagram.
http://www.pelicanparts.com/911/911_Parts/1978-83/1-7-2.JPG
I have seen earlier threads on how to test and adjust the AAV.
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Bill Krause
'79 911SC Euro