94 Town Car Mystery (not) Starting

We have a 1994 Lincoln Town Car in our fleet (55,000mi) and it has just been dropped in my lap for repair, I NEED HELP! The car was driven all over town, parked on an errand and then refused to start when we got back in. It would crank, but not start. Naturally, I assumed it was the fuel shut-off valve and re-set it w/ the switch in the trunk. Still nothing. So, called AAA and when the guy showed up he wanted to hear what it sounded like cranking and of course the damn thing fired right off like it never had a problem. We have shut it off and started it a dozen times now with no problems, but I would really like to not get stranded somewhere. Anyone have any ideas as to what to look at as the problem? Thanks a lot for your time, all!
-Matt-

Hey Matt, wrong forum.. this is Conti's
Anyway, there's some discussion on this "no start" problem running Over here.... (http://www.lincolnsonline.com/cgi-bin/ultimatebb.cgi?ubb=forum&f=3)