I have a 175hp 1995 Johnson Oceanrunner that feels like it is misfiring at 3500-4000 RPM. Running below 3500 RPM I do not experience the misfire as bad as above 3500 RPM but the engine seems to skip occassionly. Above 3500 RPM I get a bucking or jerking motion intermitenly. To date I have changed the plugs and stator, check the fuel system by squeezing the ball, problem, persist. I have also disattached the power plug while engine running and I still experience the misfire. I suspect the ignition system and its componants(plug wires,power pack,coil(s), optical ignition sensor. The motor contains an OIS2000. Is there any way to isolate the problem that anyone knows prior to just replacing all componanats? Any suggestions would be appreciated.
