Recently bought a 1972 32'Pacemaker with twin 270hp crusaders. The engines are 2007 with carburetors. Navigated it from Jacksonville to Vero Beach with no issues except could not get the starboard engine over 3500rpm. Just thought it would be a throttle adjustment. One month later, the starboard engine won't go above 2500rpm. Its stops accelerating at about half throttle. Rpms actually go down a little if I throttle past half. Any ideas as to where i should start? Fuel filters? Plugs? distributor?