This must be a sensor problem. "power seems improved when fault shows itself,feels like turbo is not working and suddenly kicks in " No way that is a mechanical problem.I have a VW LT28 2001 2.5 diesel panel van,It has developed an intermittent fault and has become a lazy starter.
When the fault is present the idle speed races and when driving,applying the brakes seems to affect the smooth running of the engine.
The problem has steadily got worse and i have read different articles and suspect the air mass sensor,but would appreciate any ideas or useful suggestions what it might be.
Another symptom is the power seems improved when fault shows itself,feels like turbo is not working and suddenly kicks in ?
I know next to nothing about these engines so would appreciate any help.thanks dave.