Try another flywheel.
I had an engine do this once,
The engine I had, used to miss like this but clear up when you hit the trim button. I then dissconected the rec reg and it did the opposite (run good then miss when trimming) I replaced, CDI , coils, stator, rec reg and it did not fix it until i replaced flywheel. Not sure why but it worked.
give it a go.
Bookmarks