I got a 93 ford thunderbird that every now and then it won't start Ilet it sit for a day and it will start right up....it just turns and turns
see if you can extract the trouble codes, take it to your autoparts store and have them give you a report the OBD-II that is integral to your electrical system-- If you put the key to just the on position without turning the starter, do you hear the fuel pump pressurizing?...a fuel pump relay may cause intermittent problems?...see now I'm guessing and will look like an ass when it comes down to a bad ignition ballast~
My guess is your fuel pump is on the way out.
When it just turns over, try some starting fluid to see if it's ignition or a fuel delivery problem. I would agree with Roy and Tom about the probability of a bad fuel pump.