This may be too late, but before you go to the expense of taking it to DD or anywhere, (mainly because having someone find an intermittent problem can be very expensive and a lot unsatisfying in the results department.), try the ASE suggested test to find the problem.
It's called the wiggle test.
With the engine running, and all parameters as close to the same as when you had the problem earlier, grab a hand full of wires and wiggle, bend, jerk, pull and push on them. If the engine doesn't die, go on to a different bunch of wires and repeat. Do this until you eliminate all the wires. Now go back and do it again, trying smaller bunches of wires, especially close to any sending units or sensors.
You can also do this test at the drivers seat area.
I did the wiggle test, bend, pull, push, from the 3 (?) temp sensors which lead to the wiring block between the engine/transmission mounted on the frame. I didn't bother with the wire leading to the mechanical guage in the engine compartment. Not sure about that one.
Could not get the engine to cut out.
The bus goes to Amos' shop in Detroit - Vehicle clinic - this Monday for its rebuild, along with the seals on the transmission. Also going to have them try to coax a few more horses out of this engine setup. I've been planning this for a while, but along with the rebuild, I will mention that we do have a problem with the engine cutting out once in a while.
Was there another test I could try for the oil sending unit? I foggily remember something about that.
Thanks again - Phil