I have 2000 Mustang GT that won't stay running

After work today I got in my car and started it up ,it ran for a second then died,started it again then died again after it ran for a second,so I checked under hood nothing appeared to be disconnected,no cut wires and no cracked vac. lines and fuel pump kicks on at start,so then I started it up again then gave it gas after it started and stayed running as long as I gave it gas ,after reving the engine for about 10 seconds I let the gas go and it died,so I figured if it runs as long as I'm giving it gas I'll drive it home,so after driving on the highway for about 20 minutes I had to get off as my exit was coming up,at the end of the exit I had to stop,and the car ran fine running normal and idling perfect???.....Anyone have any Idea what wrong with my car? Thanks ...Jeff