Trouble starting car

I have a 2002 passat GLS 1.8 that takes 2 or 3 cranks in the morning or when sitting for 6+ hours to start. It'll sputter for 3 seconds before idling. Runs normal and starts normal the rest of the time as long as it doesn't sit for longer than 6 hours. It seems to be fuel related but what do I know. I've replaced the fuel filter and fuel pressure regulator with no luck. Since it runs perfect the rest of the time, I'm not sure what else could cause this problem. Any ideas would be appreciated. Thanks!