Hi to everybody, I have a avant a4 2.8l 1998, this wagon used to work well, I just did a mayor tune up of 02 sensors and valve cover gasket. Used for 2 months and the check engine came back again and it was the same sensor; the one after the CAT, but thats not the problem even with that still worked very good, I just stop the car for 2 months one morning I went to turn it on and the battery was kind of weak and I put a new one and the next morning when I went to use the wagon, it tried to start but it can't, the only way that stay on is if I stay on the gas pedal, but sound like it has a missfire and does not pass fromm 3000 rpm, I did took the computer to a place to test it and was OK, I also took the mas air flow sensor and was ok, also replaced the spark plugs and checked the fuses, also look for any broken cables and nothing, what it could be?