I have a 1983 80 HP mercury that seems to have losses power put new plugs in, a new head gasket. and when I put it back together I had to mess with the idle screws on both carbs in order for it to stay running when I throttle it down it takes a while to get on plain. and I lost 10 to 15 MPH. do not have power trim and didn't. move the pin on the transom please help