[BrianG]

I don't know much about a Muggy, but does it have a center diff? Brushless has a lot more torque than a nitro so it is much easier to have the front unload a lot on take-off. This basically unloads the motor to where it spins relatively unloaded making it hot. I would try some thicker oil in there, 50k as a minimum IMO.

That could explain motor temps, but not ESC temps. That usually means you are overgeared when both are hot. Have you tried gearing down as Lincpimp suggested? You may not like the resulting lower top speed, but it's a place to start.

Also, I would set the punch control as high as possible before you don't like the loss in take-off punch. This will help tame that initial high current burst and should lower temps.

Usually, in such a heavy vehicle, I would suggest 6s on a 1800kv motor, but that combo you have should be perfectly fine geared right.