This is the same thing my 99 Contour SE sport has been doing. The warranty expired and about 300 miles later the problem started. I fixed it with a stick of dymanite placed strategically under the hood.....BOOM no more problem......no really....took it to Auto Zone to check the codes. There was no codes and the guy said it would be best to take to dealer.....I think I will just trade it in for a civic or something LOL
If you get yours fixed without replacing the entire car let me know!
Thanks!