My sons KSF 90 A8 has started flooding out when he give it gas. It will crank up easily and idle allday but as soon as the throttle is pressed it goes dead. I change the plug and took the carburetor off and cleaned it. Do you guys have any other suggestions? Seems like the choke might be stuck on but I am no mechanic and I didn't see a choke when I pulled the carb. Thanks for your help.