I have a 1999 70hp Johnson that starts and runs fine, just it mostly runs on 2 cylinders and every 15 mins or so of wide open running, the 3rd will kick in. But its not always the same cylinder which I could find by the black plug on the non running one. It seems to jump around which one does not run. Like i said it runs on 2 most of the time at lower throttle positions. Its been to the dealer 3 times and they can find anything. Thanks for any ideas.
Correction, its a 1999 not a 1990.
Correction, its a 1999 not a 1990.