If you 100% sure you still have control and it's just the motor cutting out it it could be your speed control .Here's some things that can cause the esc to draw to many amps and cut out.
1. Make sure the motor is not meshed to tight with the main gear.
2. Make sure the belt is not to tight
3. Check for any binding in the servos and linkages.

I suspect the problem may be your bec is overloading but you lose all function for a split second if that is the case. What brand (model) esc are you using? Is the bec built into the esc or is it separate.?