Posted this before but it's slipped down the rankings and I still need help with it.
Basically I can drive the car round all day wherever I like so long as I am not going over 60mph (2000rpm) for any period of time.
Reason being is this;
If I drive at say 70 for 2 miles then take my foot off the throttle and let the car slow down, as soon as the rev counter hits 2000 rpm the glow plug lamp comes on and the engine dies. I can just quickly flick the ignition off and on and all is well again.
If I do exactly the same thing but instead of leaving the car in gear as it slows down I just press the clutch and let the engine drop to idle as the car freewheels then the engine is fine and no glow plug lamp!
I have changed the Cam position sensor and the car has 148000 miles, full service history (good filters) and not run on supermarket diesel.
Ok, thinking caps on chaps :-)