Hi there my Audi is driving me nuts its been playing up and not running right for the past 2 years, I have cleaned the Egr valve out with no luck and it has recently been to Audi to have all 4 injectors replaced and it just seems worse! It will be fine for ages but then it's like a switch is flicked and I feel the car instantly change and lack power and hesitate at low revs, but when you accelerate it still pulls well but I can hear the exhaust loudness get considerably louder and the pressure in which the exhaust gasses comes through the exhaust is considerably greater too almost as if the bore size of the exhaust is being restricted right down! No engine light comes on and Audi main dealer cannot diagnose any problem but clearly there is! Also I have noticed if I'm driving for a while when it is running badly if I turn the engine off and try to restart it the starter motor turns over very slowly and the engine struggles to start, this is only started to happen recently as I used to turn the engine off before and restart it which usually makes the engine run better again! Please are there any idea of what is wrong have you had the same problems and how would I check if the Egr valve is working properly as its all electrical and doesn't run a vacuum! Thanks for any advise anyone can give me and I look forward to hearing from you!