Ok. Your carbs have been flooding and that can give those dymptoms. Run regular gas as premium can foul plugs and cause rough running. You would only run premium if you had hi comp pistons and I'm guessing the bike is pretty stock.
If the bike is stock and you are running an open airbox lid then get a Dynojet or Factory Pro jet kit fitted. With a closed stock sirbox you can run stock jetting. If the bike has vacuum fuel tap (under the tank at the back with two hoses) then get a manual tap and plug the vacuum hose with a small bolt and clamp. They can cause issues and there are threads you can search here on how to do it.
Shoulda thought about flooding. That would explain the sudden change. And float height. 750's are pretty low compression, 9:1. Regular gas!
If you live in the US, Dynojet stage one with OEM springs. US bikes had different jetting than the rest of the world, notably leaner.