That is exactly what happened. The motor would not idle in or out of gear, so I cleaned both carburetors, replaced the fuel filter, put 10 gallons of rec 89 and a can of marine pro seafoam in the tank. It did not resolve the issue, so I assumed it was a timing issue and did a link and sync from my SELOC repair manual which said the spark adjustment rod should be at 2.5". Now the motor boggs at 2800 rpm. The problem is that I didn't take a photo of the spark adjustment rod prior to the adjustment. The motor ran at 5000 rpm at 27 mph prior to the link and sync. on a Grumman GV17SP aluminum V Hull. Any recommendations would be appreciated.