I recently bought my first Mack. It is an 85 dmm with 300hp. I think it had been sitting around for a few years but seemed to run pretty good without too much smoke. I jumped in the truck and drove it from iowa to ca. About nevada it started cutting out after being under throttle for a few minutes. I figured this was due to a clogged fuel filter so I changed it and it seemed to solve the problem. Somewhere around the same time it started to blow large amounts of black smoke when I hammer it. Now it seems to run pretty good but way too much black smoke. Where do I start?? turbo? a leak? settings on the pump? injectors? Everyone I ask points in a different direction.