hey my name is cody and i have a 97 12v auto. i pick this truck up a couple of months ago in december. when i first got it the only time that the truck would blow gray would be when it starts up when its cold and to get it to blow black was a quick pedal drop. but now a couple months down the road it start always blowing gray tell warmed up then once your cruseing it will blow black under any amount of pedal action. i normaly wouldnt care but its getting worse and the truck has 200000. it has a newer stock turbo and a kn intake and filter that i heard bad things about. so i called a couple people one said injectors one was pump timing one said low compression and then there was a return line problem. so last night i took all the return lines off and checked for clogs didnt seem to have any but didnt really know how to deal with that. It kinda started after crappy fuel was in my tank and plugged all my filter and i had to clean the tank and all but then like a month later it was starting to dump coal and gas milage was never as good. i never turned the pump up or messed with the pump. but it just seems like all of a sudden.

 

Fuel pressure needs to be looked at .. if that's ok (28-34 psi @ idle).

if that's checking out, IP timing is the issue likely