[snapier]

This sounds very similar to a problem that I just had. My Superformance (SP01400) would break up when I would get on it but regular driving it was just fine. Then finally one day I went to start the car and no spark. Took two weeks to figure out that the magnetic pickup in my msd distributor and also at the same time my duraspark ignition module where bad at the same time.
Good luck...