I'd like to know what batteries, and what motor are being used. I don't think the speed control has option to disable LiPo cell Auto Detection. Set Punch to minimum, and slowly roll on the throttle? When I see the XR8 speed control being used, I think of larger RC platforms like 1/8 scale buggies/truggies, or possibly a 4wd short course truck. With all that extra weight, and larger/more powerful motors, I think your NiMh batteries are being asked to do too much...especially if using only a 6 cell pack.