my disco has the dreaded 2,500rpm kangaroo judder, i,ve read various posts bout overboosting etc, when i changed oil last week i took off ecu to check the factory fitted oil bath, it was running through me fingers before i got it to the bench! i cleaned it all out, let it drain and refitted, i,ve checked the wastegate arm and that seems to be free, could it be the wastegate solenoid?