Sputter and Bad gas mileage

[james_c17]

Well, its been freaking cold here in SC. When it started getting cold my gas mileage has dropped a good bit. from 16-17 mpg to like 11-13mpg. Tonight a something new happened, I got to a stop sign and it spit and sputtered like it wanted to cut off. As far as i could tell there is not misfire, and It has recently had a tune up. The fuel filter has been replaced, and its getting plenty of fuel i think. Could this be the the MAF or Thermostat sticking, anything else?
i did a little research and thats what i found.

 

[james_c17]

And i forgot to mention i have the 5.0 and there is no check engine light

 

[swetrid]

Around here with winter gas and cold temps we usually see about 2 mpg less then normal.