Okay so I need some professional advice I have had my 2012 Merc 15 fourstroke for three years now I have it on a Carolina skiff j12 about a year ago it started to struggle to get on plane and feels like it’s just bogging at full throttle no weight has been added to the boat I have thoroughly cleaned the carb checked the entire fuel system for leaks bad connections fuel pump fuel filter and gone through the gas tank also checked throttle linkage made sure carbs opening up all the way anyone have any ideas the motor starts first pull idles and runs flawless but when I give it full throttle it wont go faster than 10mph? I clocked it in at 30mph when I first got it???