My car does the same thing (yes its a M6). I had my TB P/P by Smokin87TA (great job BTW)

The idle will hang a little (200-300 rpm) for a few seconds and then settle to about 900 rpm.

I can feel it happen when I decelerate (take foot off gas completely) while in gear. The motor will increase in drag after a few seconds.
It does make heel/toeing a little easier

I haven't tried changing the idle screw settings though

 

My A4 did it after I added a homemade CAI to my ported TB. It took it over a month for the computer to fully relearn after that. It would start doing again each time I reflashed my computer. Adjusting my desired airflow tables finally put an end to it.

I know how you feel - it's really annoying. And it's great when it finally quits.

 

So every time you flash the computer it has to relearn everything as if the batt was disconected?

 

Yes, it's like when the batt is disconnected. It affects idle.

 

What is the goal when adjusting your desired airflow? are you just adding or subtracting air until the car idles the way you want?

 

FWIW, I was having the same issue, my battery connection was dogshit and it kept cutting out, so the computer kept resetting, so I was putting up with this forever. For about three weeks I haven't had an issue, cleaned the contacts and torqued it down good. Did it for a while, but after 3 weeks, it doesn't do it anymore, ever. If you had your battery disconnected for whatever reason, like the one guy said, it may in fact take a month. I have a feeling it needs to go through a GM drive cycle, which is a PITA to do anyway, but after a few weeks of normal driving should be ok. I daily my car so that should give you an idea how long it'll take... ASSUMING of course it isn't a faulty IAC, leak, etc...

-J

 

If youre on a open loop tune could that effect the learning process ie take longer to learn or not learn at all?

 

Not sure if that question was directed towards me, but I have absolutely no idea, sorry.

-J

 

Yep, it's not just idle per se, but the way the engine drops down to idle. It corrects the hanging idle problem, where the rpms hang and even surge as they are coming down on decel. You have to log your idle settings and then adjust them as need be with a tuning program.