1991 Audi 100 rough running question

["Herbeck, Terry (ext. 264)" <tlh@ogpnet.com>]

All,
     My 1991 Audi 100 / 5 cyl / automatic with 75K mile that runs very rough 
and

stalls for the first few minutes after a cold start if the ambient 
temperature is

56F +/- 2 degrees. I've:
 - checked the fuel injection system out using the procedures in the manual 
and found

a flaky air volume sensor potentiometer ( which I repaired )
 - replaced fuel filter
 - cleaned screen on fuel distributor
 - cleaned screen on fuel pickup in tank
 - replaced oxygen sensor

Any tips / clues / etc. would be appreciated. Being in the software business 
I'm

suspicious of an ECU bug!

T.H.anks