p38 stops after 10 mins

hi folks,

need some help with this one, my p38 starts first thing in the morning no probs but, after about 10 mins just stops its like she has run out of diesel. i have to keep turning her over and over for a few mintues for her to start again,
she drives prefect while running.
now i took the diesel tank out last week and clean the inside out, chnaged the fuel lines right up to the pump, changed the fuel filter and had a leak test done on the injectors, the garage said no, 1 injector was the problem so chnaged that but, she still doing the same. i put a non return valve on the fuel line but still the same.
i've just about had it with her.
going to take the tank out tommorrow again just to make sure every thing is right in there.
oh the pump in the tank is working cause there is fuel pressure at the fuel filter, only thing i can think of is it must be only working at times.

any ideas would really help.
thanks all

Tried replacing/checking the fuel pump relay ?

Check the fuse box for signs/smells of burning.

i had similar symptoms on a merc i once had, turned out to be the crank sensor