Atego 815 drops cylinders

[tufty 120]

my 815 runs great for about 5/10 mins then it drops down to 2 cylinders, had it plugged in but no faults registering anyone come across this thanks

 

[WG M-B]

Injectors??????

 

[tufty 120]

did think fuel pressure so changed filters and pump, can injectors be affected by the engine becoming warm?

 

[WG M-B]

Surely it wouldn't run on x2 cylinders? It's gotta be on x3!!!
I would imagine an injector failing