Guys and girls.
Ive put together a few threads on this and even changed maps from Revo to MTM and the issue has still come back. I read on here the other day that another member had the same problem and after all the usual stuff of changing plugs, colis etc etc eventually they discovered it was a problem with the inlet manifold flap.
I dropped my car off yesterday at Audi and printed the thread out to show the master tech. He took my car home and the issues were showing up. Just had a call to say the flap in the inlet manifold is sticking and the part is being replaced tomorrow under warranty.
SO fingers crossed this may be the cause of my problems and maybe some of yours. Mine is a March 2011 S3.