We have a 1992 2300 SCR 5.7 Mercruiser. Batteries a new and good. When I try to start her, she turns over slowly and won't fire. It is not cranking slow like a dead battery slow, just like only 1/2 the speed it should. Eventually it will fire and go. After we have run her, she still turns slow, but fires quicker. Ideas? Fixes? I am sure someone has had the same problem that why I love these forums!