flooded engine

I bought a Beta Moped SL 5 about 7 months ago that is suppose to be new old stock, a couple fays ago i left the fuel line open on it and flooded the engine. The moped still runs but now it stalls out at every stop sign and isn't accelarating the way it use to. Could this be caused by me flooding the engine? Any suggestions on what else it could be or how to fix it?