[dumb_ricer]

I had an almost identical problem when I first started driving my DSM.

First I thought loose terminals, so i wiggled them and it was fine for a week or so. Then it happened again, wiggled terminals again, and it was fine. So I cleaned the terminals and tightened them, fine again. Started fucking up again a week later, then became fine. Turned out that somewhere along the line the clamp that clamps the positive lead to the terminal itself was loose, and randomly not getting a good connection. Tightened it and it was fine forever.

Moral of the story? Its something free that got overlooked. Somethings loose along the lines of the starting system more than likely. Could be a ground, or it could be something on the positive side. I'm guessing it may be the same problem I had.