Can anyone help?,mu a4 1.9tdi has developed a bad hesitation over 75mph while foot down,upto that speed it seems fine,over that when you put your foot down it hesitates like a swine!,if it was petrol you would say the plugs or leads were shot, the thing is that it seems to be still pulling and is soon upto to over 100mph!, ive just ordered a fault code reader but can anyone advise me on where to start looking, seems like a fuel prob? at lower speeds leaving in top gear up a hill its fine, a weird one!