Originally Posted by snrusnak
To kelr31: I just reread this whole post, it sounds like you have other things going on with your truck if you only get 13mpg highway even with the mileage tune! Especially if you're 2wd. My dad has the older 4.7L, 2wd, and gets 17mpg all around, no matter how he drives or what he hauls/tows. Also. the 87 tune can actually decrease the hp on some models FYI, to help prevent pinging noise and detonation, this is to help preserve the engine life. With that being said, it may still run a faster 0-60 or 1/4 mile due to crisper shifts and things like that...
My truck is actually a 4x4 with 305/45/22 tires, which doesn't help my mpg at all. From my experience I get the best mpg using the performance tune, then 87 and stock are about even, and the mileage tune actually gives me slightly worse than that, don't know about the towing tune. As I said before, the programmer probably does give me a performance gain, but I honestly can not feel it at all.
As far as having something else wrong with my truck , I don't really know. Everybody I have talked to has said I should get better mpg, but I don't so......