Better MPG out of a 2013 Journey?

I just recently got a 2013 Dodge Journey SXT AWD with the 3.6L Pentastar engine.. Needless to say by the topic of this post Im not impressed with the mileage Im getting. For the most part, its driven in ideal conditions for mpg (55 mph speed zones) and ive yet to see close to the claimed combined fuel economy estimate given for it..

I come from the diesel world as far as what i know performance wise, so i dont want to go touching this thing with my diesel ideas and end up hurting it.. Lets face it, they are 100% different animals..

I replaced the air filter with a K&N, figured that would do nothing but help, and since its washable save money in the long run.. Does anyone have a aftermarket cold air intake for them? Ive searched, with no results.. Does anyone do air box mods? With pvc toilet drain fittings and making a open port for air to get sucked in the bottom of the box?

Would changing the thermostat help? (it does in a diesel) right now coolant sits at 193-194 leading me to believe it has a 190* thermostat, so should I switch to a 200*? Or is that bad news?

Does the stability control off button do anything, really? when I switch it, the instant mpg shows about 3 mpg better, which made me wonder if maybe it disengages the AWD, but i know darn well those instant calculators cant be trusted.. When I do that, it shows me about 22.5 mpg, otherwise, its about 19.5 mpg

Ive seen SOME that the Pentastar does not like the cold weather, and given Im in Michigan and it hasnt been over 60* since Ive owned it, but come on.. Is it really that big of a problem?

Any help would be much appreciated..

Other question.. What about cold weather hurts it? Crazy idea but if its the cold air would a grid heater, like a diesel has help this? I can rig one up! haha