between me and my dad we have had 6 of these and from experience they all needed re-tuning once a year, mainly as they had to be de-tuned to pass the emmisions tests!
We just gave it to the Audi garage and they done the ecu and the car ran like new everytime, might be worth a try? beware though loads of cowboys will tell you they can do it and they cant!
Audi main dealers give you a massive discount on older cars
its much cheaper than the local cowboys and i know they will do a good job, worth checking out in your area