Ok, now that my intro is out of the way, I'll get down to business. First the backstory, otherwise, skip ahead to the current problem.

March 2017 - A friend of mine had a 2003 6.0 that he had sold to a buddy a couple years back. This guy was selling it, halfway through the bulletproof (it will be towed to the garage). After some discussion, I decided to go ahead and bite. My friend would go over, the job and finish it and it was supposed to be good to go at that point. This friend is a diesel mechanic in fact, for a living, and he knew the history. Or so we thought. Ready? Disregard the massive amount of time that goes by, he has an additional full-time job.
March and April - the job goes slow due to a lot of personal issues, including a 6.0 collision with a moose at 80 mph. Finally, we get down to business.
May - It's discovered that the previous mechanic or owner had messed up the head and bent the standpipes. Many bolts are missing.
June - The starter isn't there. At all. Neither is the fan clutch. Additionally, the power steering pump is no good and it needs a new belt pulley or two. The company we use to get the parts, which will remain unnamed, messes the order up so badly that another six weeks go by with no parts. There goes July. Refund processing, new places for ordering, there goes August.
September - Someone appears to have shot my windshield. Upon closer examination, the previous owner somehow got something big enough pinging around the turbo that the fins are dinged up. Bad alternator, trans cooler, and fuel plug. Stripped rocker box leaking oil. Four injectors replaced with used ones. September was a bad month in a string of bad months. Now we have transmission issues. I need a break, so I step back for awhile.
December - I'm finally ready to bite the bullet and find out what's up. It's minor but it's a pretty serious mess-up on the mechanic who had it with the previous owner. The internal wiring harness was left too loose, free to mingle with the driveshaft and get all damaged and let me say, what a delight. Fortunately, the damage was fixable. And then goes the main drive belt about a hundred yards from my driveway, annihilating the belt tensioner with it. Or vice versa. I fix that pretty much on my own and about a week later, I arrive home, go inside to take care of some things before work and twenty minutes later, no start. A coworker helps me do some digging and I start thinking about the ICP sensor. He gave me the jumping off point so I keep searching and come upon (I THINK) Bismic's lovely trouble-shooter. I have zero real mechanic experience but I know how to fully utilize the internet so I start making my way in. I at least test the FICM voltage (50V) and then start asking around, as I know I can quickly get in over my head. Long story short, ICP and IPR valve are diagnosed/confirmed by a mechanic friend and both replaced.

Here we are at the current issue.

The one thing that was largely going smoothly on this truck was the engine. It sounded great, according to guys I had spoken to who were more familiar with these trucks than I was. But now, another diesel mechanic buddy (who did the ICP and IPR valve) checked up on the injectors and said three are bad, supposedly none of the recently-replaced ones. She runs but sounds terrible and often tachs way too high (like consistent 2K one night just to maintain 30mph). Tomorrow, I'll check some connections. If there is a chance it's not the injectors themselves, obviously I would rather not drop another good chunk of change to replace something that may not be THE problem. Any other ideas? I had a financial line in mind on this thing way back but one of those bills sent me soaring beyond it and I'm pretty frustrated. Every guy who has looked at it is dumbstruck as to how something goes SO wrong. Hoping for a break but not holding my breath. Thanks guys.

 

My two cents- you need to have an IDS power balance test performed to determine what's going on with the injectors. This can of course be done at a dealer or you can track someone down with an IDS or a clone.

 

Yup...
Get a good live gauge on the truck and stop guessing and wasting your hard earned cash by throwing parts at it. Maybe someone on the forum lives near you that can help? Post in the state forum section and ask a member near you. You need a member that knows 6.0, a good gauge and then fix one issue at a time before removing to the next.

 

Both fortunately and unfortunately, I haven't thrown anything at it that wasn't an actual problem or anything that was guesswork (other than my own cost-free work through the no-start troubleshoot) as The ICP sensor and IPR valve were both diagnosed. The first guy does know the 6.0 engine. The second guy is more experienced with other diesels. He got a code on it but I think we will have to run a better diagnostic and the power test based on you guys' input, and go from there.

 

Make sure is the uncompensated test. Also, test fuel pressure and make sure the blue spring is installed.