LOL.. well I have litterally tuned my ranger to run at stoich and even leaner. (up to 16:1) It doesn't save you anything if you simply lean it out. Reason is the PCM sees load vs throttle position and adjusts timing accordingly. You see, leaning it out makes you push the throttle further down. That makes the PCM pull timing... which in turn decreases MPG. So at the very best you'll have spent $6 + shipping to get a net gain of zero.
I've found the best instant MPG by running the fuel just a hair leaner than stock. (stock is 14.1 and my tune commands 14.3) And by jacking the timing through the roof. (stock at 70mph is approx 26-28. My tune commands 42ish)
People forget that it takes three things to make fire. And your PCM is a lot smarter than you are at balancing the three. If you skew just one of them.. the pcm will account for it and adjust the other two.