I got the little Yazoo up and running with a good carb and tank cleaning and its a fine mower but I have a problem. The motor runs perfect for about 15 mins. then abruptly dies with no warning.You can immediatly restart it but runs rough and if it does run fine it dies again in about 5 mins but the second time it sputters abit and lets you know its gonna quit.This acts like a coil but it restarts quickly. If it were a carb problem i would think it would not die suddenly.Could it be vapor locking somehow.?