I have a four year old Craftsman 25cc blower. I have always used good gas/oil mixture and oiled the cylinder during the off season. The other day, I was blowing leaves and noticed that the engine had a different tone. I attempted to shut the engine off with the off switch (ignition kill) and it kept running. The engine eventually stalled and could not be started. I changed the spark plug, confirmed that it has a STRONG BLUE spark and again attempted to start the unit with no luck. I checked the fuel filter and removed it and it still would not start. I can get the unit running by pouring a little oil/gas mixture into the carburetor and it runs good until I idle the unit down and it stalls. The carburetor is a Walbro 229. I also removed the muffler and removed the very little carbon in the exhaust. Still... no change. Finally, I removed the mixture screw and clean out the passage with carb cleaner... no change. I am going to replace the carb to cylinder gasket, all gaskets in the carb and try this. Any other suggestions? Thank you.