It occurs to me that this sounds like an oddball problem I experienced on a (fuel injected) Gold Wing maybe 20 or so years ago. I was riding through Nebraska where I noticed that "Premium" fuel was about $.10 cheaper than "Regular." I thought, "Call me crazy, but I'm buying the premium."
I might add that this was in the hottest part of summer.
So I filled up with premium and off we went. About 30 or so minutes after my bike got up to full operating temperature it started misfiring and the problem would continue to get worse until I had to stop. Since the problem started right after I'd gotten the cheap premium I assumed I'd gotten some water in the tank. So the next town we got to I went into a parts house and picked up a bottle of "water remover." I think it was Heet brand, not sure. Since the Gold Wing only had a 5.3 gallon tank I figured 1/3 the bottle would be plenty since it was enough to treat a full size tank.
But this made the problem even worse. It didn't take long at all until I couldn't maintain interstate highway speed. I pulled off at the next exit ramp (my wife was following on her BMW) and we noticed an abandoned convenience store nearby where two riders had pulled off in the shade to take a break. We pulled over and began chatting while I let my bike cool back down. As soon as I told these guys what was happening they told me what my problem was. And they were right.
Premium gasoline in Nebraska has much higher alcohol content than regular. Don't know if it's still that way or not. Alcohol has a much lower boiling point than no-ethanol gasoline. We opened the fuel tank, looked inside, and sure enough the gas in there was stirring around on its own.
When the fuel pump picks up air bubbles and sends them through the fuel line the injectors inject less (or no) fuel into the cylinders. Boiling alcohol hardly effects carbureted vehicles at all, but it can cripple an injected system. Turns out that the primary ingredient in "Fuel Tank Water Remover" is ... you guessed it ... alcohol.
Their recommendation was to stop often and top off with regular (less alcohol). Each top-off would put some cold gasoline in the tank to stop the boiling for awhile and dilute the alcohol.
We kept doing so until we were out of Nebraska and where I could I filled up with no-ethanol gasoline for that bike. It was particularly sensitive to the issue and would sometimes exhibit the problem with 'normal' levels of alcohol commonly found.
If you're ever on a ride and you fall down, I'll be there. - The Ground