Cleaning the fuel system and the changing the oil is a good first step. But, before pulling all the electronics out, I would clean and gap the plugs and try to fire up by spraying starter fluid or a little gas through the carb. If it fires try hooking a temporary gas line to a portable gas container and see how it runs over a few minutes. That'll give you an ideqa of how the engine will run. Than go from there on replacement parts.

Drew