2015 KX450F running poorly

Hey guys, I have a 2015 KX450F that I bought brand new, I've put a whopping 12 hours on it in 3 years. Thats how much I ride lately

Here is my problem: I went out to my local track, did my warm up laps, then started riding a little harder. Hit a table top in 3rd, and switched to 4th in air to hit the rollers that were coming up after. As soon as I landed and got on the gas, the bike just died, like there was no fuel. Pulled in the clutch and down shifted to 2nd to try to bump start it with the momentum I had left. Would not fire. So I pull off the side of the track, put in neutral, and kick it twice, fires right up. Rev it up and seems like its running fine. I pull in the clutch and shift up to 2nd to head back to the truck, and as soon as I let the clutch out it dies. Kick it again, fires right up. I finally get it to go and limp it back to the truck. I pulled the seat off and checked the air filter, because the night before I oiled it up and it did seem like I had a little excess oil on it even though I squeezed most of it out that I could. Don't now if some oil got on a sensor or something. I bolted the seat back on, and tried to ride around the pits, still acting the same. Instead of chancing it I just loaded it up and headed home.

Once I got home I pulled it out of the truck, and fired it up. Shifted to 2nd and it seemed to be Ok. Weird. So I ride up and down my property (about 15 acres) and it runs through the gears fine, except when I start slowing and downshifting, it wants to die. I take it in the shed and pull the tank off, empty all the fuel. Up to this point I was mixing VP C10 50/50 with 91 non-ethanol pump gas. 91 is the highest I can find around for some reason. I got 2 sealed 5 gallon pails of C10 from a friend, he got them from work because they weren't using them, but upon further inspection I saw a date of 2016 on the bottom of the pails so they may have been old and past their shelf life.

The most I ride is about 3 10-15 motos at the track and I've had my fill, and it is not ridden super hard, like back in my "glory days", so its not like I'm abusing anything. Filter is cleaned before every ride, and oil is changed every 2 rides, and oil filter changed every other oil change.

What I've tried so far: Bought a service manual. I pulled the tank off and completely emptied it completely, put it back on the bike and refilled with brand new 91 non-ethanol. Rode up and down my property and it ran a lot better, but still having problems dying on me when slowing down and down shifting. I bought a few new spark plugs and a new gasket for the fuel pump so I can pull that off and inspect it this Saturday.

Is there anything else I could be missing? What is the best way to clean the fuel pump? Any guidance is appreciated.