1998 Mercury Optimax 225hp problems

I've been having problems with my 1998 Mercury Optimax 225hp outboard motor. Let me start from the beginning. I took my boat out and noticed it was running below the usual power. It was about 20 percent below normal. After running for about 5 minutes it would loose another 20 percent more horsepower at full throttle. The work I have done so far is cleaned the fuel by doubling the dose of Sea foam to the gas and I have rebuilt the low pressure fuel pump. I also replaced the bulb. I also changed the filters in the boat and on the motor with new ones. I also cleaned the filters within the High pressure fuel pump. I made sure all the hoses were on tight and had no leaks on them. Now I have a new problem after I had done all these things. I cannot go full throttle in forward. It would hesistate and stall around 3500 rpm but If I put it in reverse it would run perfectly fine with plenty of power with no stalling or hesitation at all. I have been working on this issue for the last 3 months and I am at my wits end. I have worked on plenty of engines both gas and diesel and both 2 strokes and 4 stroke engines. I can't afford the Mercury dealers cause I just retired from the military I am just getting by with my retirement check. Please if someone had the same issue I would appreciate any suggestions.