Swapping out the OFV did nothing. And after much head scratching and net research I figured out how to check both the engine and injection pump timing. Both were spot on. At one point I had other coworkers and gearheads over, with a total of four heads under the hood of the truck. And after 3-4 hours of tinkering and such, nothing. We were about to give up and tow it to a shop so everyone left. I went to lunch to blow off some steam.
My buddy Jason calls and asks " have you cleaned out the fuel heater?" I respond with "The what?" So after some over the phone description I locate it next to the fuel pump. It is a black bowl looking thing that unscrews from the bottom of it, like an old tractor.
And this is what I found. Uck!
It was absolutely packed with brown gunk!
Half a can of brake cleaner and a new fuel filter for good measure I pumped it up, started it, and took it for a drive. Voila! More power than I've had in a long time!
Evidently the reason number one and two cylinders were not firing is they were starved for fuel as they are the last two to be fed via the inline injection pump!