There was an issue with the power valve when I first got it. I noticed it rattling pretty bad, so I pulled the covers off to inspect. Sure enough, the guy I got it from lost the bolt that acts as the stop for the actuator arm and replaced it with a button head. I replaced that with the correct bolt and all seems to be good with the valve now, though I have not observed it while running with the cover off. I'll add that to the list of things to check. The jetting issues did not change after that.

This chart helped me understand which settings effect which throttle position...

Thanks for posting that. That will be a big help when I dive back into this this weekend.