I had a problem with my car being slow to start when there was a lot of moisture in the air, such as after a rain or when it was foggy. Turn the key, indicator lights come on, but the car doesn't start. Pump the gas, a few minutes later it starts. Once started, it starts OK the rest of the day. Batter was tested and found to be strong.
After two trips to the Ford dealership, an intermittent problem in the starter was found. The starter was replaced and the car starts promptly every time.