clogged fuel filter?

[<JB>]

I have a Yamaha 150 on a 21ft Mako. Top speed is 35. Last weekend the engine would not move boat above 22 and then after *****ing for a few hours top speed returned to 35 and then slipped back to 22. Bottom is clean. RPM seems to be fine. I checked the external fuel filter and it appeared clean. Any thoughts before I take it to a mechanic? Thanks.

[<boats.net>]

Check compression,install vacumn gauge in fuel line to check for fuel restriction, test ign system for a component breaking down, dirty carbs will cause that also or bad fuel pump