Took boat out (two trips ago) stopped and fished went to move boat fired up great let warm up a minute pushed on throttle and motor acted like it was misfiring or being choked out switched off restarted ran great. Latter that day did same thing except I just cycled key real quick off/on motor kept running but acted great. Got home changed ignition (wanted second key anyway) also checked fuel line connections (since I had just re-routed to prevent rub) also changed primer bulb (no particular reason). Took boat out over weekend ran great 35 miles out just like before went to change fishing spots and when I accelerated had same problem as before turned off re-restarted ran great stopped fished went to move again started boat ran perfect til I accelerated and any thing over 4000 rpm an d the motor was shaking and mis- firing or backfiring (hard to tell) any stopped to fish started again everything fine headed home slowed for cargo ship went to accelerate and same 4000 rpm problem ran in a while at 3700 rpm then eased it to 4000 no problem then up to 5500 no problem slowed back some got close to ramp tested by stopping (not switching off) went from zero throttle to 5500 no problem did this twice came home flushed motor and now I need to find out issue. One more thing bought boat a year ago eliminated VRO per omc mechanic's guidance I now premix 50:1 johnson mineral oil and had boat out several time after VRO delet no problem except optical sensor went bad on very first trip (not related to VRO delete just putting all info and symptoms out there. I'm mechanically and electrically inclined and work on most stuff sounds like timing advance intermittent please any help where to start? Thanks for any help.
