My 2002 2500HD has about 52,000 on it. During February, I noticed that every time I try to pas or accelerate quickly or power up a hill, the truck will loose all its power and start to slow down (at 1/2 throttle or more). The turbo spins at light throttle, but as soon as I give it a bit more, the turbo stops whining and all power goes away. It has been about 8000-10000 miles on the fuel filter and the weather has been in the teens or lower for temp. As for the fuel filter.....the truck would act like this when the filter was 1000-2000 miles old. Seems worse when it's cooler outside. I added in some Power Service diesel additive (to prevent gelling - white bottle) and that didn't seem to do much. It's at the point now that I can't even pass a car on the highway or get out of the way of a big truck. Also, every now and then I get a whiff of diesel when the truck is parked and not running. Nothing appears to be in the oil and I don't see any on the engine anywhere. No trouble codes either. One more thing, I have been running both B-20 fuel and regular fuel (regular when the place is out of B-20).