Here at Cedar Garage we have seen many problems on these vehicles suffering with turbo failures and causing the symptoms mentioned above. Sometimes it can be as simple as a seized actuator or a split turbo hose but unfortunately often the turbo is the failure.
Firstly when we get the vehicle in we will carry out a test routine to identify the exact fault and then trace the cause of the fault so that the fault does not reoccur in the future. Often when the turbo fails it is down to a lack of oil getting to the turbo. If the seals in the turbo go completely then the engine can over rev on its own oil causing catastrophic engine failure.