went yesterday and motor would crank barely but when i went and put it in gear it would go dead, dead. changed hose, changed gas and fired her up today. looks promising if it will do this on the lake. the gas in the tank is probably three months old and can't really remember if i added additive. i did add it in this test deal. i have a half tank left in the boat. my question is should i fill tank, add additives, namely sta-fil marine and seafoam, or drain the half tank i have in there now and start over???