intermittent miss

[leftseat150]

My 1984 Johnson 60 has an intermittent miss on both cylinders. When using a timing light, I get an intermittent pulse on the light along with a change in exhaust tone. I've verified the timing light is ok by testing it on my truck. So far, I've replaced everything but the flywheel. That includes coils, plugs and wires twice, power pack, timer base, and charge coil. I've disconnected the stop wire at the power pack plug (black and yellow) with no effect. I've also disconnected the rectifier and stator also with no effect. The carbs have been soaked and rebuilt, I've replaced the fuel lines and have been through several tanks of fuel. The motor runs fine once you come off idle or at least it appears to, unless it's just not noticeable while underway. Any idea's or suggestions?? Thanks for your help.