Eddie Hotrod

The intermittent start problem on my '85 3.2 seems to be back. I thought I had this one licked, but yesterday I was left stranded 100 miles from home. I had driven about 100 miles the day before no problem. Next morning the car wouldn't start (turns over great, but no fire). This has happened before and usually if I leave the car for an hour it would start fine. But yesterday it was definately not budging, so I had the car towed home. Get it off the truck outside the house, and it bursts into life at the first turn of the key. Truck driver laughed his *ss off as he held out his hand for £160.
I have a good DME relay, the coil is fine and there's fuel getting through. The roadside mechanic tested for a spark and there wasn't one. So this is certainly an electrical problem. I think it's either the DME unit, or maybe the crank sensor, but I'm confused because once the car starts it runs really well. If there was a dodgy solder in the DME, surely the car would sometimes run bad or die whilst I'm driving, but it's always fine once it's started. Any ideas what could be going on?
All help much appreciated.

upallnight

Flywheel reference sensor is only used for the initial statup, not use for the engine to run. Over time they lose their magnetic abilities.