I have a 2007 (225) Opti, and I had a similar problem. I checked all the fuel hoses from the tank all the way to the outboard, replaced primer bulb, check the fuel filter and even rebuilt the fuel pump. After all that it still wasn't idling. Finally I had enough and took it to a marina. I told them all the things I checked and changed. They told me that there was an air leak in the fuel pump body. They found it by taking a fuel pressure reading from the fuel pump to the motor. It wouldn't hold fuel pressure, as it was sucking in air. I would have never found it as I don't have all the equipment to check it. $1000 later new fuel pump and diagnostics, it runs great. If I would have known this, I would have not rebuilt the fuel pump and just bought a new fuel pump. Just another thing you could look at, not saying this is the problem with your motor.
"Practice, practice and more practice, and if you think you're good practice some more". circa 2006, Cadman