1987 Johnson Coil Breaking down?

[BlazerSS]

I have an 87 3cyl Johnson it is an outboard jet. While running down the river if I pull down to 41-4300 RPM you can hear what I would call a stumble. If I increase the speed to 4500 RPM it doesn't do it at all. The motor has new Champion marine plugs, new plug wires, 2 of the 3 coils have been replaced with CDI Electronics, the power pack has also been replaced with a CDI Electronics brand. I don't know about the stator or timer base. I didn't replace any of the electronics parts. Does this sound like a coil going bad?

 

[racerone]

Test run with a timing light.---Start with # 1 and repeat with 2 and 3.--------You lay the light on a seat and observe the flash of the light as you throttle up.