Ok, a little background info on the motor before i dive into what happened today. ~240K miles, 6.5 spec'd IP turned down a little bit from stock, and 6.5TD injectors. No timing advance, its set to stock. No turbo, and until today it had a stock air cleaner/snorkel setup and stock J-code intake manifold. I had planned on a turbo, but it never happened. So move up to this week. I finally get arround to changing my fuel filter, its been nearly 30K miles, i know its well overdue. The truck isnt smoking at all anymore, usually it smokes some. I change it, and it seems to bring some fire back into the motor. She is smoking under full throttle, but nothing like the absolute smokescreen it had been when i first did the pump and injectors. I figure great, i wasnt loosing my pump. This was 2 days ago. Today, i decide to finally install my ported J-code manifold, and cut my filter housing into an open element. I dont care about noise, or hearing my passengers because i never have any, all my friends my age drive nice cars and would rather drive theirs than ride in my slow noisy K5. Anywho, back on topic, i go to start it up, and it doesnt quite want to start. Now, it is cool out, about 50* and the truck has sat since i did the filter, but still. It surges a bit, making me think there was still some air left in the system, no biggie. I let it run for a couple min and shut it down. Go back out a couple hours later, and it doesnt want to start again. So i give it 5 seconds extra glow and it flashes up, no surging this time. I take it for a drive, and it is noisier than i expected, but it is also 9:00 at night, so it seems a bit louder than it really is. I get it warmed up to about 150*, and from a stop mash the loud pedal. She definately has more pickup, it actually pushes me back a little bit. Then i look in the rearview mirror and realize that i am leaving a trail of thick, black smoke. WAY more than usual, im talking scary ammounts here. I saw my friend in town at a stoplight, and used him as a guage to make sure that the truck really is quicker, and it is. I hang with him longer than usual, so its not my imagination. So, here is the situation. It should be getting more air than before, and should in theory be smoking less. Its not, its smoking more, a lot more. This, in theory, should mean that its getting less air, and should be a little slower, right? But its not, its quicker than before. It could be getting more fuel, but i changed nothing other than the filter, and even right after that it was back to smoking how it was after i first turned the pump back down and set the timing back to stock. Is it backwards day today and nobody told me, or does this scenario actually make sense to anybody? I havent brought it to the track to get hard numbers, but it is quicker, even my friend noticed it, he commented not only on the gawdawefull racket i was making, but also that i didnt dissapear into his rearview mirror by 20mph like normal. I really dont see this all steming from the fuel filter, but i suppose it could. Anybody have any ideas at all?