my guess is bad gas. 10% ethanol gas goes bad in a short time sitting.
I noticed in my fuel cell you could see it seprated with moisture in it.
got down to mine sputtering/popping/not running, then a good flush with NON-ETHENOL gas fixed it righ back up with nothing else.
I did have to drain carb to remove water in the bottom of bowls along with draining the lines/pump/cell.
it only sat about 2 months here in Fl. summer heat.
it sitting from last yr would need fresh gas if it is 10%-E crap.
did it have summer blend or winter blend.
I have noticed getting bad gas when they change out for the season. price drops and they sell it off before it ALL goes bad.
I don't buy gas when 1/2 the pumps out of 15 are not working/tanks low and they are emptying it out.
I wager bad gas.