i noticed a difference when i bumped my timing to 18.5* in the milage and with it bogging in 5th gear. when i was in fifth gear at 40mph the truck would hop in the rear but afetr i bumped it i get all the way down to 30mph in fifth gear and it still dont jump just pores the black smoke

 

Wel that whats i'm talkin about mines and automatic though but i'm thinking about going to the marines so.... I might sell it or even wait till i get back and fix it up.. I would like to do alot of stuff to it..

 

Bumping the timing will get you better performance up top and have an added benefit with say a 3k, 4k, or 5k GSK setup.

 

if it rolls the coal it could be due to a different fuel plate, a badly tuned afc, no fuel plate at all, .. how much boost are you running and what do the egts look like?