2009 3.0 tdi, last few days can hear a noise like a air intake noise changes with revs etc, however not always there. Yesterday started car engine RPM all over the shop going from 900 rpm up to 2000 and back and up again in seconds, turned off, restarted it all was ok. Today took it up motorway for 9 miles no issues at all. Then dinner time went to start it and it was again all over the place, this time thou wouldnt sort itself out. Called out AA who discovered that the intercooler pipe to the air intake was collapsed under heavy vacuum. Took off pipe and engine ran ok. Managed to drive car home about 5 miles obviously well underpowered etc due to pipe been off. I tried putting pipe back on again and it went back to square one all over the shop . I can only presume a turbo or blockage issue. However as i said after yesterdays effort all was ok for 9 miles at 80 mph on motorway. any suggestions greatfully received
