my audi a3 1.9tdi year 2001 has not got alot of power it is very slow when you pull away and top speed is only about 80 mph it it has been to a garage and they can find nothing as yet wrong what could be the problem

sounds like your air flow meter is out of it's parameters,try disconnecting the air flow meter to see if that makes the car any better.It puts the ECU into a default setting for the air/fuel ratio
if the car is better like this replace the airflow meter