Ok so I've been researching a little bit and have found a few people have posted about issues with the temperature sensor on the head. I watched a video someone posted with a bad sensor and it sounded similar to how mine sounds at full throttle. It does not just stall out it is a rhythmic "brap-bog-brap-bog..." (Sorry that's the best I can discribe it.) I picked up a new sendor and its being shipped out. What's the worst that can happen? I'm out twenty bucks...
Also after comparing a couple SBN 44s I have on hand to my 46, I found the 46's throttle shaft to be very sloppy (1:8"+). I ordered a genuine Mikuni throttle valve kit. I'm wondering if at full throttle air was leaking through the sloppy bushings causing it to lean out. We shall see.
I'm also going to cut some new carb mount gaskets out of some 1/8 Viton material to make sure it's not leaking out of the joint between the intake manifold, spacer/cable mount, and carb. I couldn't get the studs to come out of the manifold in order to check for a square surface. I'd like to eliminate the metal cable mount because I had to make it fit with the wider bolt pattern of the Wetjet manifold and carb and it might be a weak point for a leak. Unfortunately I would have no way to mount and adjust the throttle cable if I do eliminate it.