Yes, I read that link you posted. It seems a bit ridiculous that it has been a known problem for this long and VW/AUDI hasn't come up with a fix yet besides expensive cleaning.

I can tell you that my 2007 S8 with 48k miles is back at the dealer, for the 3rd time.
1st time - Check engine light went on, diagnosis=faulty manifold, replaced under warranty.
2nd time - Check engine light went on after 24 hours; diagnosis=carbon deposit and faulty fuel injector #2, replaced and repaired under warranty.
3rd time - Check engine light went on 6 days after I had it back; diagnosis=Audi wants all fuel injectors replaced under warranty. Wonder why?:p

I hope this solves the issues. I am a very spirited driver who only burns Mobil or Shell and I am not going to be refused my therapy because of some carbon build up...:D

Yeah I guess I have to check if my service contract covers that. I don't like anything getting in the way of my lead foot! I tried to fix it by replacing my spark plugs and coils. After pulling them they were black from carbon and gray from the fuel cleaners I've been using. It didn't help so the carbon definitely needs to be cleaned out of there.

Had same issue
 

Turns out there was always in the gasket around the spark plugs and oil was hitting into the spark plug chamber.
if you remove a spark plug do you see oil?

I replaced all the plugs but this was a few years ago so I don't recall if there was any oil present after removal. I still had the problem so I ended up going to a dealership I previously worked at to get it checked out. Even with a discount, it cost me $5k to get the carbon buildup cleaned out and have 3-4 oil changes afterwards to ensure everything was removed. My extended warranty didn't cover any of it. The car's performance was much better after that but ended up selling it so I wouldn't have to repeat the process again.

Carbon build up can be a common issue on these direct injection engines. It's recommended by Audi to use the fuel additive every few gas tanks to clean the carbon off ( part # G 001 780 M3 ). If it gets too bad the intake manifold will need to be removed and carbon cleaned off by hand... it's a process... all in all probably take you about 6 hours.