I had a simmilar problem yesterday. I run a hobbywing xerun 10.5t in my pro10 with a 120A v2.1 and all of a sudden it stutterd and stalled a little on the straight. I could drive slow but that is it. After a lap or so i could drive normal again. First i thought it could be the temperature protection but my motor was only 50-55 degrees after the race.
Today i opend the motor and found out that the 3 screws that hold the sensor board had all backed out almost completly. I already thought the sensor socket felt a little loose and now i know why. The sensor board was rattling in the motor. I hope it solved my problem.