Update:
I've cleaned the spark plugs, ground points, checked the tank vent tube (can blow through it), and replaced the fuel filter again. I also removed the airbox to verify that the fuel return line is unkinked. All of that helped a little, but after awhile the bike would continue to sputter/surge above 6k RPM. Another point: I have the vent stub by the fuel cap, but my fuel pump screen doesn't have the little vent fitting, so I've just removed the vent hose. Then I cleaned the fuel injectors, and while doing so may have stumbled upon a clue.
After removing the fuel line at the most forward part of the rail, gas was continuously pouring out. I remember doing this in the past and having a very small amount of gas come out, but not in a continuous stream. Now I'm thinking that it must be a hole in the submersed fuel line within the tank? Planning on removing both fuel lines and submerging them and blowing into them to see if there are any splits or cracks. What do you guys think? It couldn't be related to the fuel pressure regulator could it? HALP