On the HP pump there is a valve that controls the third piston, this piston is disabled when power exceeds 2/3 presumably to reduce the fuel pressure and loading on the pump. One side of the valve is fed via fuse 25 in the engine bay, the other side is switched low by the ECU to disable it.

I think this is worthy of some investigation as it does seem to fit your symtoms.

sounds like a weird one cant belive its had so many parts, sounds like a deffinate fuel problem engine will cut out with either too low fuel preassure or too high fuel preassure ,is your scanner capable of reading fuel preasure, like some one has said the 3rd piston actually comes in at high revs boosting fuel presure for demand so at idle u would exspect 300 bar and as u rev engine it should increase too 700bar if u could read this then we could see what was going on, and i could advise futher !