Hi i am new to this forum and hopefully someone may have an idea what is up with my car. I have a 1999 ACK 2.8 v6 Quattro Avant with a auto tiptronic gearbox, three weeks ago i had a problem with a fuel smell coming from behind the back of the car when running, took it to a garage and it was diognosed that the both lamba sensors were fauly so i replaced both of them, a week later the mot was due so took it to the same garage it failed on emmissions due to poss a faulty sensor as it were only on one side, so replaced that one retest both cats were now faulty replaced them both, now the problem since all this was replaced when driving under light throttle no prob, accelerate up to 70mph take foot off then replace under light load it feels like its firing on two cyls take foot off the wait a few seconds like the car is catching up on itself its fine but the problem is always there. took it back to the garage and was told that ther is no power going to one of the lamba sensors checked wiring must be a faulty ecu, bought another ecu a AUDI dealer fitted it but still no feed AUDI dealer found broken wire to sensor, thought this had cured it but have just returned yesterday from driving to paris and back and it is still there and now the car will not idle very well AUDI dealer said throttle body need cleaning would have been nice to know before 700 mile round trip. love the car but do not want to keep throwing money around.

all these problems seem to be after the mot and after new cats, sensors fitted

any help would very much be appriciated

cheers