Hi all i have a 2000 reg A4 1.9tdi and it doesnt seem to have much power.. Driving around town the power seems ok but as soon as i go on to the dual carriage way it will eventually reach 80mph and i cant seem to push it much more Then when i reach a small incline the power will drop dramatically.. I put a code reader in and it reads P1556. I have Changed the MAF, The turbo works as i can hear it when i rev the car Can anybody shine any light on to the problem Thanks