If I trim up or down at low idle (while in gear), the engine dies. Engine usually starts right back up, but I had to kill power on my main switch to recover a couple times. It dies at both switch locations.

-trims up and down fine with engine off.
-trims up and down fine with engine running and in neutral
-trims up and down fine at higher RPM
-Battery is strong and fully charged

So, I fished hard the last 2 days and didn’t have any issues, as long as I didn’t trim up/down at low idle (in gear).

I plan to inspect the wiring and connections this weekend. Suspect trim motor is just pulling more amps that normal and stalling the engine. Thinking bad ground, corroded connectors, or bad motor.

Any other thoughts or advice before I tear into it?

Looks like you're thinking in right direction if need anything give us a shout

Mine would do something similar. Die while trimming up. It was a broken wire in the harness, inside the rigging tube.