I have a traxxas electric 2wd truck with an aftermarket engine. It really hauls for me anyways and has always ran like a champ. Its called a speed gem 2. has traction control. Anyways, its not working too well right now, I hit the accelerator on the radio and nothing happens.... everything else works good, steering is fine and dandy, new batteries in radio and well charged humppack battery in truck. Sometimes if I turn both wheels forward real fast and hurry up and hit the accelerator then it goes, but it dies down quick, almost like the battery is dead, but i'm positive it has nothing to do with the battery. I just re-soldered the power wire the other night, so i'm pretty sure that it has a good and stable connection and no wires are touching each other or disconnected, etc.
I did take the engine off the car (checked the gears and all that looked fine) for a minute and manually spun it and hit the accelerator and it worked fine then(seemingly). I put it back in and took it outside, it ran for about a minute before it started dying on me again.. same thing. I'm not sure what's up.

Any Ideas guys?.. thanks