Citroen C5 2002 2.2ltr electrics cut out when engine put under load?

My C5 has developed a problem when you press the throttle pedal more than half way down the electronics
shut down stopping the engine, The only way to restart the car is to activate the central locking wait a few seconds then unlock the car and the engine will restart. The car will drive perfectly on a light throttle
and can achive 80 mph with no problem but as soon as you put the engine under presure it cuts out.
I have already replaced a lot of parts to try and cure this problem but with no luck. Can anybody help? it's driving me mad. here is a list of parts already replaced
most of them came from a C5 which a friend of mine was breaking that car was running perfectly before I took the parts, so I would not think that they would have exactly the same problem.
Parts changed:
Throttle position sensor (Second hand)
Injectors (second hand)
High presure pump (second hand)
Common rail (second hand)
Fuel filter (new)
Camshaft sensor (new)
crankshaft sensor (new)
timming belt (new)
Fuel pump (in boot new)
tranmitter in steering colum (new)
Has anybody got any more suggetions