Thanks for the help, it is very much like hitting a wall in terms of there is no noise to suggest missing etc it just gets to 4krpm rpm and stops, in the lower gears sometimes it seems to hesitate a couple of times but once again there is no apparent noise from the engine.
As for the tailshaft its only the steering that is vibrating, the wheels do need a balance but it is much worse than it was before. I'll check to see if any wieghts have fallen off and also check leads, and spark plugs tonight if i can.
Oh and just incase someone suggest it i doubt it's a BHG radiator coolant is still nice and green and oil is still err black but no milky substances (thats another story).
Oh and exhaust leak i doubt, cos after topping up the oil yesterday i left the bonnet up and started it, let it idle for about 10 mins and didn't hear any obvious leaks. Once again i'll check tonight though.