These are all 2-strokes right? I'm in Cali and I run the beejezus out of 2-strokes with good old pump gas. The cans sit mostly in the winter, but they still work fine as long as the gas does not vent the aromatics away ...
I have three year old pump gas in an outboard tank mixed at 32:1 with my home brew TC-W3 Quicksilver and Motul 2T oil (50/50). Been using that brew for about 10 years now. Voluteer at a local Park as part of teh forest maintenance group and we have a bunch of mod'd and hot saws.
I get ribbed by guys that insist on running non-ethanol fuel. They run TrueFuel too. I don't bather. Yes I have carbs go south every once in a blue moon. Funny thing is they do too ...
Mostly pump gas eats the fuel lines and they eventually break in the tank. So it's an onerous job to re-thread a new line through all the nooks and crannies. But once done, they're good for at least 4 years.
I have two Echo saws, one weed wacker. They must have 1,000 hours on them if they have a day. I got Husky and Poulan and WeedEater too. Same deal. A lot of hours. Some sit for months, some run weekly. None exhibit what you describe.
So the common denominator is either you or your oil... I can't see how the operator could cause this. So I'm betting it's the oil. I'd just try something entirely different. You can't hurt what already not working. So how about some pump gas and some Quicksilver outboard oil as test. See if it does better. At least that would eliminate the TrueFuel and the Torco ...