1975 mercury 200 20hp bogging at high rpm on the water

[Stevanvalk]

I started out with difficulty starting and since the motor sat for a long time, started with buying a carb rebuild kit, cleaning all carb parts and replacing everything in the kit, jets, diaphram, gaskets. Replaced both plugs, replaced the ball on my fuel line and started with fresh fuel. In my driveway it starts rough cold but first pull after its warmed up and will run fine for an extended time at idle to high rpm.

So I took it on the water and it runs fine in high for about 2-3 minutes and then starts to shake and bog down, almost sounds and appears to be misfiring a cylinder. I can back the throttle down and run 1/4 throttle fine, then rev it back up after a short time and it runs good in high for a couple minutes and bogs again. If it stalls on its own at any point, it is difficult to start, if it is on the verge of stalling and I hit the kill switch, I can start it again on the first pull.

Again, carbs have been rebuilt, plugs have been replaced, fuel ball stays firm, runs fine in the water filled drum in the driveway.

Things I've heard as other possibilities are:
1. Inside layers of fuel lines can be collapsing
2. Reed issue in block
3. Bad coil

Any ideas or suggestions?

 

[Stevanvalk]

Discovered there is a blue wire coming from the ignition switch box to the stator, that the insulation is rotted and the wire inside is corroded. Obviously this unit will need to be replaced but does anyone know if this could possibly diagnose the specific issues above