Regaining lost MPGs

[DaleJrDolphins]

Thank you barryware. I will have that checked. I was thinking that the more likely case was the cat conv and muffler getting older and blocked up but didnt want to lead the conversation down a road intentionally....wanted to see where it went naturally.
In the case of the tires though...i have been watching for even wear and it "seems" that they are wearing evenly. The other thing that made me thing exhaust system was the somewhat small shuttering with the engine/exhaust that I hear/feel....but thats mostly when its colder outside. Any thoughts to that?