I think non ethanol premium grade fuel is the best for long term storage but that's all I use in all my cars and small engines. Expensive but never have a fuel issue.
Also once a year put a can of seafoam in all the fuel tanks.
Yeah that e85 is garbage and attracts moisture from what I was told. I always use premium in my small engines and they always run better. At the end of every season I always add Sta-Bil and has never let me down.
Anytime I go away on a long drive I always put injector cleaner in the 300. Purrs like a kitten