Well, I've had that problem before, but lucky for you your car started! It happened one day after it rained. My car wouldn't start and I went nuts. It sounded like it wanted to but didn't , so i changed my spark plugs and it started once. The spark plugs wasn't the problem, it must've helped dry something near the engine bay. then i got starter fuel and sprayed it near the throttle body. got a little closer to starting, then finally did. So I drove it to bmw. long story short, they changed one of my sensors. I'm not sure which it was but i think it was the oxygen sensor. O, and the bmw mechanic recommended i take the CAI off. So, all in all, i'd say get your sensors checked out and make sure there isn't water up in your syster. O and make sure your using high octane gas.