If the engine runs for a second and dies there could be a lot of things. From a pats antitheft system problem to a bad plugged catalytic or bad fuel pump. Check this link https://www.justanswer.com/ford/7ck6g-2005-ford-freestar-3-9l-v6-car-cranks-normal-starts.html

 Depending on model year Thought there was some TSB to prevent water ingress. Might want to remove the PCM connector and check for Green Death ,Use electrical contact cleaner and seating and reseating  the connector several time might help for awhile, but the one I had issues with needed to get the PCM replaced.