Diagnostic code said #2 is mis firing

I have a 2006 Ford Taurus SEL 3.0 gas engine. The car starts fine in the morning, but the rest of the days it turns over repeatedly 3-5 seconds before it starts and can smell gas. Have already replaced fuel filter, splark plugs and wires. Someone said it is the fuel regulator, but I CAN"T FIND IT. Where is it???