I ran it today in slightly milder weather.

After about an 8 minute run, before the pack could finish, the steering became erratic, slow and unreliable, I even had the reciever shut down for a few seconds. I was getting full power from the motor, but the steering was way slower. The ESC was 160, the motor was 180 and the batteries were 118.

What the heck causes these motors to run so hot?

I think the BEC overheated or something.

Judging by the battery vs motor temps I figure maybe it's running a higher ratio. But if I lowered it the esc would get hotter.

To be honest I think that the heavier can insulates the heat and the normal L can motors will run cooler. I don't remember the L can getting any hotter than 150 in my buggy.