Extended crank, hard start

My vehicle has been having intermittent starting problems. The engine will crank, but will not start. So far I have replaced the fuel pump, the throttle sensor and the crankshaft sensor. After replacing the fuel pump, it seemed to be better for a short while, but started having the same problem. It sounds strange, but the problem seems to happen most often when it is hot outside, no so much after being warm from being driven, but after sitting in the heat. So far, I have been able to get it to start after a few attempts, but it seems to be getting worse and happens more often. Once it has started, the car runs perfectly fine, no stalling, hesitating or loss of power. During all this, the check engine light has never come on.

This is probably not related, but I also had both my low beams go out at the same time on headlights that were only about a year old. Every other light and blinker worked fine, the low beams just quit. Changed the bulbs a couple weeks ago and have been okay.

At my wits end. I love this car and have not had any problems since I bought it new until now. Help!