I have 99 a4 1.8T quattro and its at 110,000 miles.
i brought mah car into a shop becuz the engine would cut off as soon as i start the engine and they said my throttle body was the problem so i replaced it and they told me the catalytic converter was clogged and that's wut caused the throttle body to go bad..
now with the new throttle body the engine doesnt cut off and stays on but the idle is very weak and rough
they said the catalytic converter became cherry red after about 3hrs of engine running and i read some stuff online that a4z got problems with the O2 sensors...
do u think i should change both catalytic converter and the O2 sensors?
would that solve the problem or should i be considering other parts that caused the problem too?
your inputs will be much appreciated thanks.

 

first off i would have your car scaned for any codes. and you only have one cat on your car and it could be pluged

 

Yes, definitely get the codes read. That will tell you what is wrong with the car. It could quite possibly be your CAT. I just had mine replaced and the mass air flow sensor replaced. They said my CAT was totally destroyed. Audi's exhaust systems are total crap. Same type of problems with my VR6 when I had it.