2004 Yamaha 150HP 4 stroke outboard rev. & speed issues

[pathfinder101]

I have a 2004 Yamaha 150HP 4 stroke outboard. It does not rev above 3000RPM under load and only goes less than 10 mph.. I also noticed that there were alot of black burned residue in the prop area... It just started doing this today... I did install a new Yamaha fuel filter and new fuel lines but noticed that the fuel line is a bit smaller than what it should be.. I also installed a Garmin fuel sensor that attached to the fuel line... The fuel line is suppose to be .38 diameter but I beleive I installed a one size smaller fuel line.. Any ways, my question is: Can this cause the motor to have these issues or do I need to clean the injectors or is it bad fuel (water mixed in)? Any help would be well appreciated.. Also, I've attached a thru-hull strainer in the bottom of my hull. Right in front of the lower unit of my motor.. Can cavitation from the thru hull strainer be the cause as well?

Thanks,

Jeff

[boats.net]

Need to run a compression test, run fuel pressure and fuel vacumn test to see if have a fuel restriction or loss of fuel pressure, check fuel pump diaphram to see if has ruptured diaphram.

[BaileysBoat]

It ran well before all the mods? What RPM and speed did you get?

Me thinks you shot yourself in the foot.