Would appreciate some input with this, the fault is intermittent but makes the vehicle undriveable. Seems to be worse with gentle acceleration, as the accelerator is over approx 30% a hesitation develops that gets worse, the auto box will even change down but the vehicle does not increase speed. Backing off and applying power again sometimes causes same symptoms, sometimes it accelerates as it should. The only parameter i can see that is incorrect is rail pressure loop difference. Expecting to see approx 1000bar during acceleration, getting less than 200. Even if the engine misfires for 20secs, no codes are stored. Vehicle is well serviced, has new fuel filter and filter housing, and new air flow sensor, all genuine parts. Fuel quality is good, and there is no in-tank pump on this model. Access is very limited on this vehicle so difficult to test component, any ideas would be welcomed, have been told it is 18hours labour to change fuel pump or pressure regulator! Sorry forgot to add, engine code is P9X 715