1999 Mercury 25hp FourStroke Bigfoot issue

[blankenship_kevin]

I am not real sure if this is a question for here or the prop section. I have a 1999 Mercury 25hp FourStroke Bigfoot on a 1998 14' Carolina Skiff Standard. This hull is called DLX today. It is running a Mercury Quicksilver 12 pitch, 3 blade aluminum prop. I have done everything I can do to determine if I am getting all the power this motor has. From my research I think the boat will weigh 500-600# with equipment. With just me in the boat it will plane and run around 24mph. If I add another person it will not plane and stays bogged down around 11mph. The motor starts and idles great. I have confirmed that it is running on both cylinders. I had the prop completely rebuilt by a local prop shop. I have put one of the generic tachs like the tinytach on it. I am using Mode 1 which I have read is the correct setting for 4 strokes. It idles at right around 775-800 but WOT will only get about 2200. I know that is far less than it should be. I took it in to a reputable local marine mechanic and he told me he found water in the gas. He instructed me to empty the tank, hoses, carb, etc. and start over with fresh gas. I have done that and there was no change. He also said that I might need to go down in prop pitch but everything I have read says that you get roughly 100rpm for every inch. Is that a cut and dry figure or is it possible to get more rpm gains from it? I am at the point where I am ready to ditch this motor for a larger one unless I can determine there is something wrong with it causing it to be underpowered. Does anyone have any suggestions? Thanks in advance!