Using your sniffer, open the hood, is the smell strongest more from the far driver's side front? or more towards the middle. As someone else said, the fuel rails do leak, and mostly at first start. The metal will be cooler in the morning when you first start it and you can generally see the leak at the fuel rail if this is the problem. Science class...warm = expansion, cool = contraction. However, gas vapor expands more when warm, making the smell more prevalent warm if the problem is a vacuum leak. The evap canister is on the driver's side very near the rear of the headlight. There are vacuum lines that pull off or loose from various junction areas traveling to the canister.

Hope this helps,
Chris