[patrickt]

About ten years ago I had a similar intermittent electrical problem. I was able to pinpoint it by having temporary 12v lights wired to the critical circuit points so that when the problem occurred I could just look to see what light was out and that tipped me off to where the problem was. Try wiring a light to the On/Off 12v+ feed to the MSD box right at the box itself. Take her for a run and, when she cuts out, tell us if the light is still on. Likewise, have a second light wired to the always-present 12v+ and 12v- feeds to the box. Since that light will always be on, what I did was just hook it up with alligator clips before a run. If it is indeed an electrical issue, this is a pretty good way of identifying it. It won't spot everything (like a flaky coil), but it will eliminate a lot of possibilities. I do like the MSD Hi-Vibration coil, and that's what I have. But don't start replacing things until you've exhausted the light bulbs trick. The problem with an intermittent fault is that you can accidentally "jiggle" a bad connection somewhere in to working right and you think you've fixed it, but you really haven't.