BMW Repair: 320d overheating, combustion temperatures, fuel compression

Question
i have a 320d and it overheats when on the road when it is idling it has no problem and when i drive around for simple thing it has no proble i have changed everthing the expansion tank thermostate waterpump even the head gasket. the last was the head gasket and the car does not accelerate as before it will not go pass 100km. i yo can give me any insight i would apreciate it thanks.

Answer
Check all the crutial elements:
Timing
Fuel
compression
check the fuel pressure, the fuel timing (CIS) and valve timing (are you sure you put the timing chain/belt on correctly?)  it sounds like the timing is off, causeing it to increase the combustion temperatures at cruseing speed but keep them low at lower RPM.
let me know more about whats going on so i can help you more