Dear fellows, I'm asking for your help in solving a problem regarding my beloved Audi. Actually, I'm begging for your help, because it's driving me crazy. The car (A6 2.5 V6 AFB quattro tiptronic) suffered from power loss and excessive fuel consumption. Obviously, no error codes were stored. After 3 painfull months and a bucket of cash spent on new MAF, MAP, TCRV and a few others, I'm still there. Also cleaned the intake and the VNT. I'm about to start shooting mechanics. Or myself. Today I found by accident something that might explain it. With the engine idling, everything seems fine. But when it's revd, i can see that in the clear tube between filter and pump air bubbles form. The higher it's revd, the more air she drinks. when it reaches 3000 it's basically running on air. When it gets back to idle, the bubbles disappear. Given the fact that I've tried so many solutions by now, I would like to have the members opinion on what would be the cause for this and, if possible - the solution. I followed the fuel lines to the tank - no leaks. In the engine compartiment - no leaks. One of the rubber hoses coming back from an injector seemed a little tired so I replaced it. It wasn't that because the bubbles are still dancing in my fuel line. What could it be and where should I start? Your input is higly appreciated. Thank you.