1988 mariner over heat alarm 2 stroke v6

[trevin11]

here is a list that i have done to try to fix it

changed empeller 2 months ago

changed tsats

when i drive around for about two or three hours the overheat alarm comes on and to get it to stop you have to fast idle for a minitue or so unpluged the overheat sensor when it goes off noe change im about to pull my hair out help me plz