Just following up. I did a bit of "all of the above" per your feedback. I reduced the grades some more where possible, I think it is much more gentle now. I also applied a drop of oil to the motor bearings, and made sure it wasnt over greased. I also made sure to oil the rolling stock I was using, most were fine but a few were not so free spinning, stopping after 1 revolution if you "flicked" it.
Good news is it hasnt gotten hot after my 30 min ish running sessions. I may need to smooth out or lower/raise some sections in the future, but I think it is 95% of the way there.
I will post a pic or video of the trouble spot in question so you get a sense of it.
Well, sounds like you had friction in quite a few spots. Your rolling stock's rolling resistance can add up quickly.
Wheels should definitely spin more than one revolution, that is for sure... and realize you did that with the car off the track, i.e. no weight/pressure on the bearings... under load (sitting on the rails) it had to be worse.