I think I know what my problem is BUT I would like to hear from those of you who know engines. My 1993 Johnson 48 SPL runs good EXCEPT for top end. It has a rythmic stutter. I might assume this is rev tach?? It seems to be electronic in nature and not fuel related. Maybe I have the wrong prop on? Too high of revs at full throttle? When I throttle down a little, it stops. Can you assist?? Thanks, Jake