i have a 1991 mercury 60 hp. motor. the motor runs fine all the time. but if i run the boat wide open for thirty minutes or more when you go to slow down the motor dies. it will start right back up but will not go above 2500 r.p.m.? i have a few guys tell me that i am loosing prime on my fuel line or it could be the cdi box? any help would be nice