I had several 'breaks' in my wiring. The way I figured mine out was with the individual 'mag' check. Engine died when flipping the number 1 toggle. Had to wiggle the wires while it was running!!
I then had to pull the braid back to find more. You can easily see the internally broken wire when you bend each individual wire.
My opinion is the wiring harness is borderline quality. I ended up putting tie downs every few inches to stop any further vibrations.
I still have rough running but not nearly as bad as previously.