I hope you've got to the bottom of the fault, I'd be interested to know what was the cause. If not, I have a tale...
Out of interest, how did the engine perform just prior to packing up each time? I only ask as I had a similarly annoying intermittent problem with a car a while back; in the seconds before cutting out it would seem a little hesitant to rev and then sound flat and stop, wait half hour and it was perfect again for another half hour... turned out to be an internal collapse of the exhaust!
