So - I've waited weeks to get the truck fixed - knowing it was going to cost me so much that I'd cringe at the bill... And then, after I finally took it in - I got good news and bad news....
The bad news - its an injector - from what I hear one of the scariest and maybe costliest fixes aside from an entirely new engine. They told me it basically imploded, broke in half leaving pieces inside the engine. They say they got is all out - I'm hopeful.
The good news - it was covered entirely under waranty - DOH... What was I wating for?
I got in my head that it must be the EGR valve because its been replaced on that truck so much, and everyone I mentioned something to had agreed. I've since read that this 6.0 engine is notorious vor EGR (as many Fords seem to be) and injectors. I'm very hopeful that's my last problem with one. We'll see.
Happily the truck seems to be running just fine again. I've put on a bunch of miles just running around and it hasn't skipped a beat. I'll need to let it idle and see if that changes anything, but the fuel mileage seems to be what it was before the break, and I've been trying to push it a little to see if it'd chug - so far no problems... Yay!