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Get a inductive timing light. Run the engine and when it bogs put the timing light on the top cylinder, look for the flashes then repeat on the other cylinders. We are looking for a bad cylinder. If you find one not firing, then trade it with another cylinder. If the non firing moves with the coil then the ignition coil is overheating and needs replacing. If it stays on that cylinder then the problem is in the switchbox or trigger. Let me know what you get. We'll go from there.
When it bogs down immediately after you can start it but only runs 1/2 throttle correct? If so, that is the time to check the firing with a timing light, you should be able to do that in neutral.
From what you describe the stator is bad. Your stator has a high speed and a low speed side. It would appear the high speed side is not working. As the rpm goes up on the low speed the voltage goes down until it can't keep the engine running, rpm drops and it starts running right again. If you have a peak reading voltmeter you can check this by putting your meter on the red lead from the stator, you should have about 180+ volts.
With the wires being bad I would recommend replacing the stator anyway. Some of the same wire is inside the stator. The yellow wires carry AC voltage to the rectifier for the alternator, charging system. Yes you do need a special tool to remove the flywheel but it isn't expensive. DO NOT remove the small bolts on the top of the flywheel. I'd bet 99% the high speed side of the stator is bad.