whenever i go on vacation, i'll come back and the G does not seem to start smoothly.

If I have not started the car for over 5 days, this is the symptoms.

the battery is fine, it'll crank but does not turn over.
on the second and forth try, i'll crank and hold the key for around 5 seconds and will still fail to start.

on roughly the 5/6th try, i'll turn and let go after 5 seconds, i'll hear the car turn over and the engine will start. but at very low RPM (almost close to a stall) and i will hear the rpm slowly build up and the engine go back to normal within the next 10 seconds.

after that, if i drive everyday, my car is normal.
It's automatic btw if it matters? any idea?

my friend said it could be the fuel line being emptied? i should repeat and leave the key in the ON position to prep the fuel through? before trying to start? this never happens to my old cars (usually battery dies before anything else).