2006 Mercury 50ELPTO Run Issues

[Cory86]

Last year I started having problems out of my outboard (50 ELPTO Mercury). Before start up I would pump the bulb, trigger the enricher valve several times and the motor would start. It would idle perfectly fine. At launch boat would go and get on plane with no issues, after a few minutes the motor would start to bog down, lose HP and speed. Would stop boat put in neutral and sometimes the motor would cut off sometimes it wouldnt. After a little while I could take off and the same thing would happen. One day I decided to pump the bulb while the motor was dyeing and the motor went to running as it should. HP and speed both there. Well I replaced some CDM modules and spark plugs because I thought one was failing. I also replaced fuel pump, cleaned carbs and replaced fuel lines because this mainly sounded like a fuel delivery issue. Well after that it ran good one time and went back to doing the same thing. Pulled carbs and made sure they were cleaned also checked floats to make sure they didnt have holes in them. What I did find is that the middle carb out of three wasnt getting fuel which is odd to me if the top and bottom are getting fuel. I have also emptied and cleaned the fuel tank but have done nothing since then because I gave up. Does anybody know of issues such as this and some avenues that could fix it other than a boat mechanic?