My '89 Yamaha 115 was noticably lacking power and would intermittantly surge to normal power (as if a plug was not firing properly). I replaced all plugs and for a few minutes it ran good but soon after the loss of power was back. You could feel it surge and drop back at varying speeds. I just took it out of winter storage and had a 1/2 tank of gas (with fuel stabilizer added) and topped it off with fresh gas. Thoughts on this would be a bad spark plug wire but beyond that???
