electrical short

I would make sure you have solid + and - at battery to engine and main power circuit then try a fused 12v wire direct from battery to coil, road test over bumps for a test,
if it does stall you know that circuit is ok. sometimes it's quicker to eliminate good circuits. If you have a tach, try disconnecting it from the coil for a test. Like doing a draw test you eliminate good circuits till you find the bad then dissect it till you find the problem. I disclike intermittent electrical problems they can be very time consuming but easier than body work.