Why don't you try this motor from HC.
In the reviews you can read some have had great results in some MT's (I think it was an E-maxx).
It's a beastly motor.
http://www.hobbycity.com/hobbycity/s...hless_Inrunner
I also read about some problems with it running hot. But you could just drill some holes in the front and read endbell to be sure...
And ofcourse It's super cheap for some awesome power!
Oh and that first motor you used, was that a KD36 motor from HC? They are known to be low quality... The KB45 motors however aren't! ;)