1995 johnson outboard running rough

[xtroutx]

I have a 60hp 1995 johnson outboard that runs real rough at about 1/2 throttle. I changed plugs, gas and gas filter and no change. At 1/2 throttle I am maxed out on power. Checked spark at all three plugs and seems to be fine, all three plugs seem to be getting used about the same. any help would be appreciated.Also can this engine be hooked up to a computer at a boat repair shop to test what is wrong with it.
thanks.

 

[boobie]

Re: 1995 johnson outboard running rough

No computers on this mtr. Take it out and run it where the prob occurs and pull one plug wire off at a time and see if you have a dead cyl. How did you check your spark ??