I've heard of Seafoam, never used it. It is highly spoken of on a John Deere forum (of course, there also those who always say "snake oil" to everything) I'll give a try. I will be that if I took that carb apart I would a metering flapper that is stiff and the saw floods. Plulled the plug, it was saturated and so was the inside of the cylinder. After blowing it out, letting it dry and trying to started (no luck), pulled the plug, it and the cylinder were soaked in gas/oil mix.
Yeah, the gas these days is junk. The crap they have in their formulas are rough on those small engines. The additives help but it's still junk. You can buy those engineered fuels and they are near flawless but they aint cheap either. I put an ethanol additive in my fuel and I make sure I keep fresh fuel around. Once it sits for a couple months I dump it in my truck and get new. Can't be certain how much the additive helps. There are also fuel stabilizers in that additive and I believe many of the 2-cycle oils have stabilizers in them. Beyond that I will run some Seafoam in a tank of gas from time to time. Seafoam is pretty good for removing the varnish crap that these fuels leave behind. I even use Seafoam in my truck to clean the injectors. Does a real nice job. Dump a can in the fuel tank per the recommended ratio and run the tank down as far as I can. I have also used Marvel's Mystery Oil. Good stuff in fuel and the crankcase (so is Seafoam). Seafoam is more of a cleaner and Marvel's is more of a lubricator but I think there are elements of both in both.