I really did have the same thing happen on my race '21 a year or so ago. It drove me nuts for a long time. It ended up being a blackened connector inside the PGM 16 pin connector.

I cant remember what colour wire it was now. Look at your lower coil and find the same two wires at the PGM. Take the pgm off and look at the pins for those colour wires. Mine was very black. I cleaned it up with some contact cleaner and all was well again.
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If I have to take the carbs off once more...