I finally was able to replace my ICM and MAF and cleared the codes. Car runs great other than each time I come to a stop and let my foot off the throttle the idle drops to the point it almost stalls, then bounces back up, then drops just a little, then steadies at normal idle. It has stalled completely once but I still don't have a cel yet. I'm assuming that the engine management system needs time to relearn how to run the engine efficently with the new parts- would that be a correct assumption? And what's normal time frame for this to happen?

I am not ruling out the possibility of a vacume leak as I've experienced loopy idle before cause by that, but I have checked several times and so far have found nothing.

 

are you 99 or 99.5? if you're 99.5 i believe you have to do a TB alignment which you can do with vag com or sometimes leaving the key in the on position with the engine off will do it. if neither works check for a vacuum leak. audiworld.com has a diy on that

 

It is the earlier 1.8T, AEB, built in August of '98... no DBW.

 

aparently it takes about a day- seems to be running fine now.