7.3 Intermittent crank and no start after injector cup replacement

[nwtech]

Hello, first time posting here, My name is Andrew, I work for an engine re-manufacturer and machine shop. Im in charge of the so called "warranty department" here, and really its me fixing and installing all the crap that this place pumps out in a hurry and would like it done as cheap as possible. Anyways I have a customer's 2000 F-550 flatbed farm/service truck with a 7.3, in for having diesel in the coolant, typical symptoms of injector cup failure, and within the specs of our warranty, after pressurizing the engine, bypassing the radiator altogether, one cup on each bank had bubbles appearing. I was authorized to replace the two bad cups, and used the specific tool for removal and install, I wanted to do all 8, but theyre cheap asses, also they didnt authorize me to replace injector o-rings either, after putting it back together, it fired right up ran it up to temp, I had to leave early that day but the boss drove it a bit and was fine, a co-worker drove it home and it shut off and died in an intersection, had it towed back and fired cold that morning. Oil level is full, as well as the HPOP reservoir. Base engine oil pressure comes up when cranking but high pressure oil sometimes wont come up on gauge installed on cyl head, yet will run with a squirt of ether after replacing the high pressure regulator, high pressure comes up to over 4000 when cranking and runs for a bit pressure fluctuates around 500 and dies if tap the pedal and let off, also the ICP sensor had a little oil when I unplugged it, and the idle will be rough if unplugged while running, Im leaning toward a bad ICP sensor, but not a pump yet, it was fine when it arrived. A little long, but any input or help would be much appreciated, Im finishing a 5.4 install in the morning, and installing a 3.0 Ford next so the 7.3 is on the back burner for a little while, Thanks