Cold Start Stalling

My '97 A8 (4.2l) has been stalling out when first started cold. If I give it a little throttle it will stay running unless I take my foot of the pedal. The RPMs will jump up briefly as the idle valve tries to kick in, and after about 30 seconds the idle valve starts working normally and it runs great.

I've replaced the idle valve with a brand new Bosch unit (for $302!) but it still does the same exact thing.

The check engine light does come on with an error of intermittant power to the idle valve (don't have the actual code right now).

Does anybody know if there is a temp switch or sensor that controls the operation of the idle valve?

Any help is greatly appreciated.

Cheers,