Urgent help with "defaults"

Hello you love.
I drive an audio s6 4.2 v8 344PS
now a small description of my problem.
It started when I bought the car that he had detonations on all 8 cylinders.
So we started with new lampbasons, kats new, new ignition coils, spark plugs, injection nozzles,LMM, etc just everything that costs a lot of money. then a tuner got me to throw an eye on the tooth strap.new on it and saw that the old one was wrong about a tooth. wow. Decommissioning. with weak load a minimum jerking but he did not want to get rid of it. I was exactly 2000km happy. my engine lamp went on again and what does it indicate?? Inflammations, but only on a cylinder bench. 5-8. Now I'm standing there like a little dope. does anyone have any idea where else I could look??
thank you in advance