well im going to try the knight sport chip and see if it helps

Alright. I kind of had that problem with mine. It wouldn't want to idle at all unless I gave it gas. And I couldn't figure it out until nearly a year later (kind of sad I know) I had everyone look at the vaccum lines and everything, the wiring, the injectors, the turbo.. and FINALLY it was a boost leak.. it was on the 90 off the compressor housing to the FMIC piping. It was about a 3inch gash.. But I fixed that and the car ran great. So hopefully that can help you.

EDIT: Also. I forgot, when I car was still N/A.. the ECU took a ****.. and it would send the car into a limp mode, running on 1 rotor. The reason for that is when the Digital Oil Metering Pump goes bad on the S5's it starts to send a bad signal to the ECU and if you don't change the pump after a while, it will fry your ECU and your car will constantly run in this mode from the moment you start it. That's all my ideas though. Anything else I wouldn't really know. I hope these help. Sorry for the post again.. stupid editor thingy wasn't working.

i installed the knight sport chip and it is running a lot better, i did not think that the chip would work but its running right now. go figer