I recently upgraded my Rustler to a brushless system. I have a hobby king 120a esc, a Dynamite 3s 8000mah 30c Lipo, and a 4600kv motor. Got everything set up and there is a little cogging at startup but sometimes it just stops going like it has no power at all; I let it sit for like 2-5 seconds and it will startup again. Thanks for the input and help.

So I figured out that one reason the car was stopping was because when using the 3000mah 8.4v nimh the motor was pulling more amps than the battery could supply.
The motor has a max amp of 87 amps. So the Dynamite battery can supply up to 240 amps and the esc is rated at 120 amps continuously. No reason for the car to stop b/c of lack of power. Sometimes when operating the car will literally stop and the throttle will not respond but the steering will continue to operate; I walk closer and eventually the throttle will respond again.

Anyone have an idea or dealt with a similar situation?

With that much power it's probably creating a lot of heat and the esc is shutting down, Maybe a good thing for you because that power is gonna tear up the drivetrain.

Check that all the wire connections are good. Soldered correctly, Sounds like something is loosing connection and loosing power so it is reseting.

@asc6000 - Yeah I was just thinking 4600kv is probably too much. I was at the Hobby Store and told the local guy I was running 76 spur/22 pinion and it was getting hot. haha He told me to get my gear ratio up, it would make it even more I controllable but would get the temp down. I think I will try to find a motor with about half Kv I have now. Thx.

@lstmysock11 - I did. I resoldered all my connections and am pretty sure they r good. This motor with 76spur/22pinion is creating a lot of heat. Thx.

Check the manual with your esc and see if it has a overheat shutoff. If it doesn't then my guess is wrong. You could use a temp gauge to see how hot stuff is getting but here is a simple analogy that will help.
I relate the heat of a motor to a hot cup of coffee. A nice hot drinkable cup is about as hot as you want to get stuff, if it's too hot to pick up and drink it's HOT. Same for the motor. Hold your finger on it for a few seconds, if it's just hot it's probably ok, it it's HOT then you ran it too long and or too hard.
Drop a couple teeth off the pinion. Also don't run a long time, check the heat every couple minutes.
It sounds like you know you are pressing the limits. Good, it will save you a lot of trouble and money later.
Smart noob.

@asc6000 - The esc does have a high temp cut off. Yesterday is the first day I actually got to play with it. I just drove it around on my track in the backyard and yes the motor got HOT. Even the tranny case was warm. It is hard to control it now but I did change gears and that moves my final gear ratio up by like 3. something. I did not get to play today as it is raining today but I will let u know how it works out. Thx

Bump due to edit of original post