My 2005 160K miles Passat 1.9TDI (AWX) has developed a vibration that comes up through the steering. There is a rhythmic whump whump whump sound at about 20mph, and a vibration that increases with speed from 50 upward. Tyres on the front are fairly new and pressures are checked OK. Vibration still there if knocked into neutral and coasting so doesn't appear to be engine or transmission related (still original clutch/DMF). Also have just changed the injector loom so not that either. Help or suggestions as to what to check. Someone suggested inner CV joint...how to check?