2003 F350 6.0 crank won’t start
 

Pretty new to the diesel scene. Has egr delete kit, 175cc/30% injectors, and sct livewire tuner with custom tunes. Bought it about 2 months ago. It had a code getting thrown for injector #6 high voltage(P0277). It threw another code for injector #4 high voltage(P0271) about a week ago. Now it won’t start just cranks and cranks. It does sound like it wants to start but it won’t hold an idle. When it does start it idles really rough and almost sounds like it loping. When I drive it down the road it only hits about 40 mph. I changed the oil, oil filter, and the fuel filters. Tested the FICM and has a steady 48v. Changed the ficm harness. At this point Im lost on what else it could be. Anyone have any ideas?