Engine/Transmission (1994 - 1998) engine braking causing sputter/ chugging?

[JTEdieselram]

Whats up guys?? have not been on here for a while, but I have one more for you to ponder on! I still have my 97, I drive it daily EVERYWHERE, but recently I have been making some trips through a few mountain passes to lake roosevelt to run my jet boat, and have encountered huge issues with coastine down hills for a long ways. If the truck coasts (with torque converter engaged IE engine braking down hill (I do not use an exhaust brake) the engine will load up BAD, I mean BAD, it starts to blow white smoke from the un burned fuel, and will chug, pop, and spit along with huge clouds of white and black smoke when the accelerator is re-applied. I run a large dragon flow 13mm pump with dragon flow injectors with 18 degrees timing, and never ever have problems except for when I coast down hill??? It is really getting on my nerves, and I need to fix it, any sugestions?? anyone ran into this before?

 

[Missouri Mule]

Could you be lugging the engine??