Possible Vacuum leak
 

I put a post up before about crappy fuel consumption, and some one on here told my to change my M.A.F. sensor I did and there was no improvement. So I took my car back to Advanced Auto and the code the guy told me was converter below efficiency bank one. He then told me that I might have a vacuum leak or my converter is breaking down. The engine has 108,300 miles on it I have changed the M.A.F. sensor, spark plugs, and the upstream O2 sensor I am about to change the down stream sensor as well as the fuel filter and oil just due to the mileage. If any one has run into this problem or knows some one that has please let me know I am tired of watching my fuel gauge drop two days later. I have a '03 Mk4 GL AVH engine code if that helps.

On another note does any one know what bracket I should use to install an aftermarket radio? I can only find ones that say they go into American cars, or Japanese cars. Any help well be greatly appreciated.