I have notice that my car is hard to start but not always.

Here is how it goes:
1. Cold start=starts right up. No problem

2. Drive for 20-30 minutes. Turn car off. Immediately crank car up, no problem

3. Drive for 20-30 minutes. Turn car off. Wait 15-20 minutes. Car has a hard time cranking on the first try. Usually doesn't start. If you wait 1-2 minutes, then crank again. Car cranks right up, no problem. Like it forgot it had a problem the first time.

Any ideas...