i am not familiar with your specific engine, however
from what you are describing, and based on the fact it will restart when cold
i am thinking maybe a sticking governor spool, maybe gummed up.
when the engine rev's up when you drop the load on the engine by too fast tipping the dump
or clutch the governor weights fly out and the system reacts, drawing the spool back toward no fuel position, the governor normally would catch this and correct for overshoot to no fuel, but if the spool is carboned up on the shaft, or the flyweights are hanging up? who know's, but my bet is the governor can't catch itself and correct.
i have seen it happen on other engine's with mechanical governors, not often but it does happen, as does a sticking injector rack, which might even be more likely, seen that happen many times over the years. i would first check all the injector racks, and make sure they move freely from no fuel to full fuel without any sign of binding.
fwiw
probably someone(s) here that can be of more help
bob g