06 LBZ with 97k on it. I installed EFI live from SS Diesel Tuning and life was good. The only thing that seemed different than most was that I was blowing a lot of smoke at 1/2 throttle and covering the road at 3/4 throttle. Several thousand miles the truck will intermittently lag and puff smoke at cruising speeds (45-55mph). If I try and give more throttle it bogs down and then seems to catch up, blow out a huge puff of smoke and then run fine. The EGR is turned off but no blocker plate. Airdog 165 is at factory setting. Air filter and mass sensor is fresh and clean. Check engine light has never come on or flashed. Any ideas?