[horsa]

Might be bad gasoline if it's been awhile since you ran it and didn't have fuel stabilizer mixed in. The old gasoline might have the carburetor passages gunked up now so you can't get proper flow when you accelerate but have enough to idle. Lots of other things could be factors but would need to know more details. Was everything working properly the last time you really drove around prior to parking it? If so, that would pretty much eliminate things like timing, spark plugs, wiring, etc unless you or someone else messed with them during the down time and changed something.

Anyway, could be as simple as spraying some carb cleaner into all of the passages after taking it off the engine and removing the top cover. Let it soak a bit and then spray it out again. Dump your old gasoline and start fresh. Might be everything would work fine again. I'd go that route before doing a carburetor rebuild or even changing any settings on the body assuming it used to work as is.