This has been annoying, it causes a single "bump" when it happens, like a quick tap on the brakes.
Stock Gen4 6.2L with 2.3L Whipple. I have attached the cal and a small section of log where it was doing it repeatedly. At steady cruise, timing drops to nearly 0 for an instant (200 ms) and then returns. Holding a steady throttle it will do it over and over. I think I have every spark retard modifier logged but see nothing. The MVPI3 data in the log is just a manual switch marker I have wired in to mark areas in a log. I never see this happen under accel, just light steady cruise. Anyone have an idea?