All,
I've been searching through the threads and have yet to come up with exactly what I"m looking for.

My '99 1.8T hunts for idle and stalls on a regular basis. Even sitting still and not moving if you rev the car and let it fall to idle the car will do 2 or 3 big surges where it nearly stalls, revs and repeats until it finds idle. Once it finds an idle it does so at a regular 800ish rpm and runs fine. The weirdest part is that there is no CEL, no codes stored nothing?

I'm thinking one of the following or possibly all of the following in combination.
BAD DV?
Vacuum line from DV to intake man.?
Bad Throttle Body?

DV details: Car has GIAC software and a 710N DV....but he 710 valve and software have been on the car for 100K miles. Car doesn't have any boost issues though so I'm not sure that's really the issue.

Vacuum line: I've replaced this line in the past and it seems brittle again however I'm not finding any breaks in the line. I pulled the line off of the intake man. when it was hunting and the idle actually improved slightly which is what lead me to a possible DV issue? (am I hunting up the wrong tree here).

Throttle Body. I've come across many threads here with throttle body issues BUT they always seem to be throwing codes when there's an issue. I have yet to clean it so I think that's on my list of things to do this week but again no CEL issues pointing me towards a bad throttle body. HOWEVER, a bit of a red flag here is that I cannot get the TB to do an adaption. I've tried the manual way several times and it never happens. I tried a few months ago and we got an error when trying to do an adaption but I didn't have the instructions with me and I'm not completely sure we were doing it correctly either. *Is there a way to tell the TB is bad if it's not throwing any codes?

Thanks for any input. This stalling issue is really getting to me. The car has been otherwise flawless for it's age (165K miles) but this issue has got to be resolved.

Andy