1990 Mercruiser 454 Mag 7.4L V8. The engine runs smooth and quiet all the way up to WOT. Once I open it up she hesitates. Rpms up and down and causes the boat to jerk until I back off a little bit, then shes fine again. I just changed the Fuel filter and the filter in the carb. I also did an oil and filter change. Any ideas? Where do i begin? Do i have to rebuild the carb? Could it be the anti-siphon valve on the tank? Water in the fuel? These are the possibilities I have come up with via this site and the internet. Where do i begin guys??? Thanks Mike
