To all who responsed with helpful suggestions....
Thanks! It was a vacuum leak and I think its fixed. I guess it was the
idle stabilization bypass air tube. I'm not sure that's what its called
but its a 3/4" tube that runs parallel to the idle stabilization valve.
It had completely collapsed and gotten mushy and there was a hole
in it. The hole was impossible to see at first but blocking the tube off
to cut the air flow, immediately stabilized the idle so I took it off and
replaced it. Since this was late in the evening, and the Audi dealer was
closed, I ran down to the nearby auto parts store and picked up a 3/4"
heater hose for 99 cents. Although the heater hose is more rigid than
the original, I don't think it should be a problem.