Why does my boat motor not run at full rpm.?

The boat is a 1993 Charger b boat,the motor is a 1993 Suzuki DT 150,B Special.Fuel injected,Oil injected and Throttle Body.V-6 with 12 spark plugs and 12 coils.Has a tripple stage firing system from the factory.Set up for a full summer with fuel additive.Cleaned fuel tank,replaced fuel with 93 octane,all 12 plugs,fuel filter.Cleaned throttle body with factory suggested cleaner kit.Electric fuel pump reads 63psi mounted inline and the repair manual states the motor must have 32-44 min.presure.Motor will free-rev, but under power will not get on top of the water,like it will not get to the 2nd or 3rd firing stage.1st firing stage is 700-2700 rpm,2nd stage is 2700-4300rpm,3rd stage 4300-6500 rpm until it reaches the rev limiter@6600 rpm.One person,no gear,no water in boat.Last year boats top speed was 66mph with a 4 blade prop pitched @26 degrees.Just acts like it is in limp mode.Reads "NO" fault codes in the computer.The computer has a Fail system as to "not" leave you stranded with a dead engine.Has back-up direct oil injection,and back-up vae fuel pumps to alloy it to continue running at low rpm.As they put it,"return to dock mode" or "LIMP MODE"Can You hepl?