[GP20]

It's most likely the gas and ethanol in your area that are causing the cold start issue. It used to happen everyday to my '04 3.0i, even when I was filling up at Chevrons and Shells. Then I moved to a different area and started filling up at different gas stations and the problem went away instantly.

These days I fill up with Chevron 94 with 0.0% of ethanol and have never experienced the cold start issue again. The engine just fires up effortlessly with a really clean sound and stable idle.