Hi all. I have a problem. My boat is in israel. Four winns 2013 vista 275. Starts running a bit heavily then temperature rises up the limit boat starts warning and immediately engine goes down low speed and Engine starts to sputter Engine goes up and down low speed. When you turn it off and the engine cools down again, drive until it warms up and start again. Impeller in good condition. Anyone knows what's the problem please?