Has this happened to anyone....input would be appreciated.....Running down the lake about 80 hit the gas hard for about 15 seconds and she slows down...I let go off the gas..hit the kill..come to a stop.....tried to move the clutch by had, it seemed stuck then freed up. Started it but missed bad so I shut it off. Took the centre plug out...aluminum colour....pulled the head.. piston melted at exhaust side and torched slightly in centre. Pulled the other heads everything fine, tan colour pistons, plugs dark. That day it was -2 C, used Sunoco ultra 94 first time do to gas shortage...earlier in the day the oil light came on and then went out but it was 3/4 full. When I opened the tank there was vacum. 2000, mild port job, timing key, cpr pipes running 390 jets. Any help would be appreciated. Thanks in advance.