Turns out that wasn't the problem after all. I don't know if having the T solenoid unplugged from the airbox changes things, but with it reconnected it did the same thing today. Just as I was about to tear my hair out, I noticed that the front cylinder tried to cough every once in a while when going back to idle after a rev so I focused on it. Then I saw one wire was barely attached to that cylinder's coil. Plugged the sucker in all the way, and she revs clean. I'll continue this under the Member's Builds forum now since I started one last fall for the bike.

Now on to jetting. Yay!