random power loss...1996 evinrude 115

[dinosaur hunter]

Hi there, wondering if you could steer me in the right direction. Engine fires and runs at about 75% power, seems like its almost bogged down. Usually about 1 min from launch something happens and engine jumps rmp and runs completely normal at full power and will run normally usually for the rest of the day. This used to happen very infrequently and now is happening on a regular basis, and now it's even been running normal at load and has cut down to it's 75% power. So it appears this problem is getting worse.

I have changed the primer bulb to an OMC one, all the fuel lines look good. always has fresh non-ethanol gas...pulled the plugs and hey look normal...I'm lost..thanks