Car cutting out but still on???

[Pedders]

Hope someone may be able to help.

Last night racing I had a problem where in each heat the car would cut out about two thirds through the heat. The esc lights still on. Transponder still flashing and if you pushed the front wheels you could hear resistance on the servo. But no drive or steering.

Nothing was loose and if you turned off the car and back on again. All ok.

The only thing I have changed since the last race is the motor!! Would this be the cause of the problem??

I did add a fan to the esc thinking it could be a heat thing but made no difference. I was running a 5.5t last time with no issues was just too fast.

Motor x12 lrp 7.5t
Esc Novak havoc pro
Servo savox full size.