12V low power after running a few miles

[Jff24Gordn]

This mourning I started my truck and it stunbled bad after it started. It wasnt plugged in at 20F. I reved it up at 1500 rpms for a minute and then drove to work. Its only a mile and never got to full throttle. A few mins later I drove 2 more miles at low speeds with some idleing inbetween. It sat for 20 mins and then I left to goto Louisivlle for stuff. When I got on the highway, I had very little power, maybe 100hp. I just made it to 55mph in 1/2 mile. It wouldnt top 10psi boost and when I floored it it dropped to 8 psi. It ran smooth the whole time. Never stumbled or missed a beat. I then poured a 60 gallon bottle of standayne preformance and let it idle for 10 mins. It didnt get better, but still idled fine. I let it sat for 3 hours and then drove to town for lunch, and it had about stock power for 2 miles then it started dropping power. It was off for 10 mins then drove the 3 miles back to work and it was dopping power the whole way. It sat till 5pm and it had some power, just not all of it, and it was dropping on the drive home.
I checked the turbo, and it spins freely. BHAF is dirty, but not bad. There is NO smoke at full throttle except if I rev on it then it has a littel black. I believe this is a fuel delivery problem on the low pressure side. Either one of the screens is plugged, the lift pump is going out, the filter is clogged, or the overflow valve is bad. my fuel gauge is out, and I have 180 miles on the tank. All unloaded.
Any ideas?
I am going to Cummins Cumberland in 1 hour for a few filters and an over flow valve and a bottle of algecide to cover my bases.