[rich]

If your harness is clean, try to duplicate the failure by systematiclly isolating and moving sections of your harness. You may discover a cracked wire intermittently grounding out, or a connector that is loose from age. Heat at a wire connection will cause the additional loss of tension and a connections ablity to stay connected.(what ever) I bought a pretty nice BMW that way once. Some one had replaced a female spade connector on the coil with the wrong size. It kept viberating loose. I got a pretty good price from the P.O. when the car left him on the side of the road one time too many. check the main power lead where ever it passess through a metel bulk head. a grounded main power wire will shut the system down or eventually melt it down! Good luck