Truck in question is a 1996 K3500, 6.5L, auto, 4x4. Its got marine injectors and right at 2000rpm its got a strange jerk going on when cruising. Feels like its running out of fuel but if you go just above or below 2000 rpm it goes away and runs fine. The seller says its because of the injectors and not having a flash (or something) done to work with them. He said if you did the flash then the fuel milage would drop. What can you guys tell me (a diesel newbie) about this?