Really? See and I've always been told that the black box is garbage. Need the orange box at least. I had problems with an occasional miss with my black box. Course I'm on a rev-n-ator now. And love it. Cleared up the miss.
Back to the problem. It's gotta be electric. But if it was always there. It's gotta be something that's been on the car for ages. It does almost sound like some sort of rev limiter.