I have a 2yr old Toro self-propelled walk behind mower. It starts on the first pull every time. BUT, lately after the engine has been running for awhile and I shut it off I have to wait 10 to 15 minutes before it will start again. I replaced the spark plug, cleaned the air filter and checked the operation of the choke and thermostat hoping one of them would resolve the problem. It didn't.
