Example for when the problem happens: Car is cold, I start it up and drive less than 5 minutes to the gas station and turn it off. When I got to start it again a few minutes later it won't. The car has to sit for 15-25 minutes until it starts again, but starts right up when it does.

Normal starting is not an issue, neither is re-starting after the car has been driven for say 20 minutes and is fully warm.

I couldn't find any similar problems in previous threads, thinking maybe thermostat issue? vacuum leak?

 

You should add your car information; year, trim level, etc. to your signature line.

However, following apply to most Accords.

Main fuel relay (MFR) could be the problem. They can be very intermittent.

When no-start occurs listen carefully when you turn keyswitch to ON. You should hear the MFR clicks from under the dash, and fuel pump run for 2-3 secs and cut off. If you don't hear these sounds, the MFR may be faulty.

If you hear these sounds, then you should attempt to determine whether fuel or spark is missing when no-start occurs. This is easiest to do by spraying throttle body cleaner (5-10 secs spray) into air intake and attempting to start. If car starts briefly and runs, then ignition is OK and fuel delivery is problem. If no-start unchanged, the no-spark is likely; ignitor, coil, or ignition switch contacts.

good luck