excellent detective work Jim!!!

ya know, last year i installed an electric W/P drive on my motor at the beginning of the season.
about 1/2 way through the year is when i first started having the top end skip, but only with the limiter activated(if i dialed it back to "0", the skip is gone).

i feel like something is messing with the limiter in my car, and it could be a similar situation to what you had.
i'm going to get the shielded lead for the distributor, and hard wire the end onto the mag pick-up like you did.....its easy enough to do, and it cant hurt.