After driving a while on warm day, car won't start

2001 Windstar. When I drive it on a warm day and go to a couple of stores, on the second or third stop, when I get back in the car and try to start it, the engine turns over and starts sputtering, but pushing on the gas pedal has no real effect and then after 10 or 15 seconds it quits and shuts off. When I open the hood and wait for 15 minutes, it will then start. I haven’t noticed any problems, once the engine is started.