The last really good gremlin guy had found locally on a XXXTcr was actually a problem with metal on metal in the diff...
The truck would usually cut out after a hard landing/launch, but come right back...

The same truck also had one screw vibrating on the aluminum motor plate, but after fixing that it was narrowed down to inside the diff.

He had tried:
3 speed cons
2 motors
2-3 receivers
2 servos
various batteries
transmitters
different brand radio completely
etc.

They had physically nearly changed every thing on the truck, but it was the truck.

If it is indoor on carpet, some guys have had "static" issues on dual layer carpet landers or plexi-glass "ice" that was laid out...
That is usually cured with some spray on static guard, or increasing humidity.