I had the same problem with the number 5 & 10 cylinders and tried the same fixes...smoke testing, fuel pressure checking, MAF checking, new plugs, new coils, carbon cleaning, new injectors on #5 & #10, new intake manifold gaskets, new valve cover gaskets, compression testing, wire chasing, etc. I haven't seen a lean code for any bank other than 2. The car would misfire like crazy as the car came up to temp. I could stop and restart the car once it got hot and not have any issues. After each attempted fix, the problem would go away for a while but kept coming back. See below for what was causing the issue...this took a lot of trouble shooting to figure out...about 4 months and lots of angry looks from my wife to get it resolved. Every Audi specialist I talked to thought it was something with the ...who could blame them. The solution dawned on me when the weather warmed up and the issue went away only to return when we got a quick blast of cold weather.
What I had was the connectors for the #5 and #10 coils backing off their coils, just a little, as the car cooled down. When the car would heat up, the expansion would push them tight again. The root of my problem was the clips on the connectors being broken from the loom being connected and disconnected so many times. I think this misfire problem is why my car's previous owner got rid it and kindly didn't tell me about. What I did to resolve this after much hunting and various procedures was to loosen the two torx screws that holds the coils' wire loom in place, just a little, so that the wire loom could float during warm up and cool down. I used a little blue lock tight to keep the torx screws from backing out. I haven't had any misfire problems since figuring out that little trick.
Now, my only issue is the lean code. I bought an O2 sensor to swap out the precat O2 sensor you can actually get to and am going to make up a wire jumper for the other O2 sensor to try a fake bank swap like Jack recommended. I also got a mighty vac to check for vac leaks where Jack suggested just haven't had the time to do this yet.