12.7 detroit won't make any power

So I've got a 2002 12.7 detroit in a kw, I've had the truck sitting at the yard for a few weeks because I've been helping a guy out with some work, so the truck hasn't drove in a while. Tonight I drove the truck back to my house , about 10 miles, and it wouldn't make any power. It's about 34° out so I thought when I fist took off it just needed some time to warm up so the wastegate would open up, got the truck up to operating temp, lay into the pedal and it just falls on its face like it won't build any boost past 10-15 psi. When I got the truck home, of corse its dark out, I couldn't see anything that was easily visible, like a torn boot or so on. The truck seems to have normal throttle response through the revs but any gear over 5th and it just falls on its face. Any suggestions on what It might be?? I'm planning on changing the fuel filter, boost sensor and charged air boots tomorrow morning and see if I get any luck. Maybe bad fuel due to condensation from sitting?? I assume it's not a turbo because it does make some boost, ans in my experience when you loose a turbo you know it..

 

It was to dark out to tell if there was excess smoke or not while I was driving

 

Just took the truck around the block, I haven't changed anything yet, no abnormal smoke. The truck does have a burble to it when reving so I suspect it's a fuel issue?? I don't have a fp gauge to tell what it's getting. I'll change the filter and go from there.

 

I think I found the culprit, changed the fuel filter, I cut the old one open and it was solid black. Put a new one in, took the truck for a spin and seems to be normal. Now why is my fuel filter black? Bad fuel? Other issues? I just did a service and changed all filters 3k miles ago.