Re: MERCURY 25 HP. help w,..
luisg,<br /><br />I just bought a used 25hp Mercury and it idled roughly also. This is my first outboard so I took it to a dealer for repair. The tech replaced the power pack (switchbox) and now it runs perfectly. It is my understanding that the switchbox can cause an intermittent miss, in my case only on the # 2 cylinder. Anyway, my motor now starts and runs like new and it's a 1992 model! By the way, a friend that has owned a 25hp Mercury says the NGK sparkplug is superior to any others he has tried. I hope this helps.