I have a 2005 cummins 5.9 that im currently working on as it was my brothers old truck and he sold it to my teacher. When he sold it the idle was getting pretty rough so i took out the injectors on it thinking that was the problem and the tests showed that 5/6 injectors had serious lag to them and the other injector was seized solid. Now we just installed 60 overs and its still doing the same thing. Its got some serious smoke coming from the exhaust and there is a decent amount of blow by. Its really rough at an idle but as soon as you crank up the rpm's a bit you would never know its missing. The only thing done to the truck as far as i know is that it has a bully dog programmer in it. The next step for us in installing a FASS fuel system in it to feed the injectors. If anyone has ran into the same problem or knows what the sollution may be any help would be awesome! Kinda thinking some cylinders may be F*****. Pistons fried or whatever the issue may be.

 

Do you have access to a scan tool that can cut cylinders and determine which cylinder(s) are at fault?