Just bought an Audi A3 1.9tdi Quattro, everything fine apart from when I accelerate usually in 5th/6th. It rumbles/judders very loudly. If I take my foot off the pedal it runs fine, no judder. I'm not very farmiliar with cars so I need help. Looked online and found it could be flywheel, cv boot/joints, or injectors. Could someone please reply and let me know what to do. Thanks,
John.