Hayne, glad you were able to work everything out. I'm still slowly struggling with mine. Your description is very helpful, but i dont understand the mechanics of the tranny that well. I'll see if i can send it to my mechanic to figure out.
Last week my shop took a look and ended up bringing in a lexus mechanic. They say that while the Aux trans pump was plugged in accordingly, the contacts were not actually touching. This caused my aux trans pump to not work, which in turn caused the trans fluid to heat up. When the fluid got to certain temps, it limited my driving slower and slower until I stopped and the fluid cooled. This was to avoid burning through the trans fluid.
They swapped out the plug and the contacts are touching now. The pump is supposedly working, but there must be another issue because the P2797 code is still showing up. My symptoms are closer to yours now, as I can drive fine in engine only (No hybrid), and the car is limited to 70mph. The trans fluid is no longer heating up and causing my car to go into slower versions of limp mode. The above diagnostics and plug change costed me $600 thus far. I'll have them look at the bearing that Hayne describes and hope that is the only other issue.
Thanks