95 GMC Vandura Random No Start Condtion?

I has an astro van do this one time. very intermittent stall, no start. After driving it around for hours with the engine cover off, it finally stalled sitting at a red light, wouldn't you know it. Had no spark. by the time I get back to the shop, it started right up. I replaced the ignition coil and never saw it again. I know that on these older gm V8's that the distributor can cause lots of different driveability issues. many times it requires replacement of the distributor due to worn shaft or cracked magnet on the pole piece or the shaft losing it's magnetic properties. you can get a complete replacement distributor from the aftermarket parts stores. I would first clean and tighten the grounds on the thermostat housing and the rear of the cylinder head. then I would try a coil, and last replacing the distributor, possibly with a known good unit first.