My car is a 91 l98 a4. At first when it warmed up it would want to stall when I got on it. Then it would do it when it was warm. Now it does it all the time cold or hot. It starts everytime, it will rev with a little hesitation in park, but if I put it in gear it will want to stall out if I press the gas at all. I put a new fuel filter in it, a new iat sensor that went bad. I unplugged the map sensor still does it. I unplugged the tps and it idles up but still does it. I thought maybe the o2 when it did it hot but now that it does it all the time so I don't think so. Any one have any ideas. I have hooker short tubes into a 3" with out cats into a flowmaster.

 

Your timing is most likely out of wack. Reset it to 6 degrees.

 

It turned out to be two bad fuel injectors. One that read two ohms and one that read eleven ohms. I picked up a set of Bosch III's from Southbay and they are great.