I have a 1990 New to me 2520 it came with a very low hour 1989 mercury mariner200hp that runs great only issue is at wot it runs at 5100 rpm doing 25 mph max speed. If I try to back off some to cruise it doesn't stay on plane. I'm gonna repower next year but this has gotta do for now. Does anyone know what the max rpm for motor is. I do have trim tabs to help out with plane but don't feel I should have to use them to keep on plane. Any help or insight would be appreciated.