First, here's a brief history. The truck is a 2007 with 285,000 miles. I've owned it since it had 147,000 miles on it.

6 months ago I had the #3 injector go down, since it had so many miles on it, I went ahead and replaced all 8 with Reman Motorcraft Injectors. I also had new glow plugs and a new glow plug harness installed at the same time. Got it back and the truck ran GREAT! Better than it ever has. Fast forward to 3 weeks ago, the truck has a slight misfire and it is hazing black smoke. At this time it throws a #2 contribution code. During the past month, it had also started leaking oil fairly heavily. It would leave a basketball size spot under the truck after sitting overnight. So....I put it in the shop. Mechanic says the oil cooler is leaking so we replace the oil cooler with a new Motorcraft cooler and replace the #2 injector. I also had him do an EGR delete while he had it tore down.

Two days after getting it out of the shop, I pull up to a stop sign and the truck shuts down but fires back up with the first turn of the key so I start watching my monitor closely. Now about once a day the truck will shut down on me. It's done it with the engine cold and the engine warm. I can tell when it's fixing to shut down because the ICP decreases with throttle and the IPR opens to 85%. It never shuts down any other time. I had a new ICP sensor and pigtail in my shop so I went ahead and installed it just to rule that out but it's still randomly shutting down.

FICM is maintaining 48.5 - 49.5 volts. Battery and alternator are less than a year old. When it's running fine the ICP is around 580psi at idle and climbs over 3,000psi at WOT. The ICP ranges between 17% - 25% at idle and goes to 80% - 85% at WOT.

The truck isn't throwing any codes either.

Any idea whats causing this truck to randomly lose HPOP PSI


EDIT:
Stand pipes, dummy plugs, and oil rail O rings were replaced when I replaced all 8 injectors.

 

I assume the STC fitting has already been changed out?