I noticed some really weird behavior with 3S (ezrun 8.5T/60A kit).. this does not happen on 2S:
When I am driving at full or near full throttle, and steer while I do, every now and then the entire car goes dead suddenly (usually ending up in a major rollover due to the sudden power loss). Sometimes only the frontlights flicker. Then I wait a few moments, and suddenly it works again. The servo is mildly warm and appears to steer normally by itself, although sometimes when I move left and right quickly with the wheels off the ground, after 4-6x the lights will blink out for half a sec.
The weird thing is, while the lights sometimes flicker slightly with 2S when I steer quickly left and right, the car never shuts down. The ESC also doesn't show any signs of errors (lights are just off) and is cool.