Heat?!?

Castle Creations Mamba Max & 5700 CMS Engine installed 2 weeks ago, didn't run it til I got a 3s lipo from maxamps today... put it on the truck and took a couple quick cruises up and down the block... after about 5 mins or so... truck started sputtering a tad during accelerations from stops... and eventually stopped making attempts to move at all.

I took it down to the shed figuring the pack might not have been fully charged when sent to me... put it on the charger and when charged took it out again. Couple cruises up and down the block... still have yet to hit full throttle... when I goosed it and wheelied the truck.. when the front tires landed... I could hear the ESC beep at me... then had little jerky movements from the truck. I remember these movements from when I had first hooked up the engine and when re-aligning the wires forgot to connect the white wire... it needs all three or it jerks a little... figured a wire came loose...

I picked the truck up... engine kinda hot... burned my hand a little and on returning to the work bench and lifting the body off... noticed the male banana clip on the black wire must have heated to the point that it melted the solder... a splash of solder was put on the body when the wire jolted loose.

Engine runs fine after resoldering the connector... haven't done any damage that I can tell. But I assume this heat isn't normal. I have timing set at it's lowest setting... 19 or 21 tooth pinion, 86 tooth spur with slipper clutch (that's another thing I noticed... the smell of burning brakes/clutch when I picked it up this afternoon after the first run)...

what else can I do to keep this heat down? I have yet to reach full throttle... and have only had 2 5-7 min runs...