I just bought a 2004 A6 with the 3.0L last week. The day after I got it, it started with a rough idle and took it in to find out they never did the coil pack recall. Before that and now it is throwing the P0304 code for cylinder 4 misfire. It only happens at rpm's greater than 2400. I replaced all 6 spark plugs today and that fixed the car for about 50 miles. I read somewhere that the 3.0 has a flash that can be done to help this problem does anyone know if that is true or how I can find out if i am eligible for that? Are there any other ideas? Thanks!

 

It might be the fuel injector. Try cleaning for any carbon built up and check again.

 

what would be good to use to clean the injectors? 44k?