I had more or less the same problem at the nationals this weekend.
At the start of the first final, I drive to my starting position half a lap further and as I'm almost there, the ESC dies. I have steering, but no throttle. A quick off-on and it seems to work again. Half a lap after the final had started, it dies again !

. Swtich off-on and it works again for half a lap. Then I decided to quit. Sometimes the ESC LED blinked orange.
It didn't do it again in the 2nd or 3rd final.
It's an LRP competition (no TC spec) on a 5.5T sintered motor and I've been using it for almost two years now. Never had a problem. Strange thing is, I'm using the same motor and cells as last year.