I feel your pain.
I drain/empty the fuel out of any two cycle machines now when I am done using them. Also, I never mix more than a gallon at a time. Try 93 octane too. I only use Star Tron (the blue one)fuel stabilizer.
The other thing if you live close to a marina, many will have gasoline without ethanol in it. I know there is a website that lists fuel stations that do not have ethanol.
I now use something called Sea Foam....a marine engine additive to the gas. It works rather well.
I do the same.
I use PRI-I in my boat, weedeater,snowmobile, lawnmower, snowblower,etc.