Car will sometimes go dead when coming to a stop

We've had our Crown Vic for 6 months and today, and for the third time since we've had the vehicle, the car went dead while coming to a stop (I was pulling into a parking space and it just rolled dead - the two previous times we were waiting to turn left at a traffic light and it went dead once while turning and once while just beginning to accelerate into the turn). After it went dead I tried cranking it up again and it cranked right up again and since happening it has again cranked right up. It also did the same thing the previous times it went dead. I need to find out why this is happening b/c I don't know when it will "not" crank right up again after going dead if and when it does it again. Today, the car had between 6 and 7 gallons of gasoline I'd just put in it (regular unleaded). I changed the fuel filter approx. 3 months ago. Any advice?