On the surface, this one sounds a little off the wall but if you think about it, it's possible and I've heard guys swear this is what happened to them...

If there's crap in your gas tank (rust, gunk, whatever), it is possible that as you drive, this stuff is sucked up against the sock filter for the intank pump. As the crud builds up, it gets harder and harder for the gas to pass thru the filter until your car finally starves for gas and dies. As the car sits for a while, the pressure in the fuel line slowly bleeds back into the tank and effectively backflushes the crud off of the sock filter. Eventually, you are able to start up the car and start the process all over again. It's a PITA to change out the intank pump/filter so I'd exhaust all other possibilities before I got into cleaning out the tank and doing the filter/pump swap. BTW, if you do do this, take this opportunity to put in a kick-ass pump to cover future mods and 10 sec. timeslips. Good luck.