Low mpg also code p0443

[SirMusicMogul73]

Hi I have a 2010 sho and am only getting 8 to 11 mpg and have error code p0443. The car runs fine except the low gas mileage.would this code be the problem ? If so what should i replace? 3 shops have told me to replace 3 different parts. I have new plugs just haven't put them in yet. Also when i fill up with a full tank ,you can smell gas 15 feet away. But don't see any leaks.Any help would be great Thanks