Ok I have a strange noise, thinking its a fuel pump. Sounds like its picking up air. I'm assuming that it has two pumps one to feed the engine pressure and one to balance both sides of the tank. No change in performance. It's intermittent. So at the moment I'm thinking it could be the second pump on all the time when I shouldn't be( if there is one).
Any ideas, 2001 1.8t AVJ(so no fuel return) quattro.