If you still have problems after R&R'ing the ignition system I would suggest the wiring harness. Do a search on M119 wiring harness and you will find that due to manufacturing these harnesses with some sort of biodegradable insulation, the harness (wiring insulation) does not last well at all. Very common problem for M119.

New harness is $400 - 500 IIRC, and it is a reasonable DIY from my research. More about this also at 500ecstasy.com.

Rgds,
Chris W.