+1 on the waterpump. I've just replaced mine and the engine is quieter now when its idling, sounds smoother.
Will
The water pump is only s few thousand miles old, it may be Chinese though so it could be dead. I will be pulling the motor to replace engine mounts and a clutch and PP upgrade so I guess I will pull the WP out as see whats up there as well.
Thank you all for the ideas.
I forgot to update this, sorry.
The problem was pressure plate. Who would have thought reusing stretch-bolts 2 times would cause a problem!? Yeah, turns out when you do reuse them they tend to back out of the crank and cause a terrible vibration that in turn starts to back out all the other bolts in the engine bay. New 210mm pressure plate, clutch, flywheel and all bolts, problem solved.