Since last fall my 40 has been reliable and trouble free - until last weekend. While cruising about 40-mph it suddenly shut down. No sputtering at all, just died. I coasted to the side of the road turned the ignition off, then went to re-start and it fired right back up. I ran it a couple more miles incident free. Motor is stock, but i'm running petronix ignition in stock vac retard distributor. I checked all the obvious wire connection to and from the coil and battery, and all seemed good. Any ideas? Thanks!