MGM 16018 Cutting out at 1/2 to 3/4 throttle

[Finnster]

Sounds like a LVC issue to me. You could always reprogram. Try it set to 6V and see if it works. The fact that it stops doing it in "race-mode" where all safeties are off tells you its a safety feature kicking in, and I don't think its a current limiter w/ your setup.