Hi Big Blue and 2010 Inferno,
Thanks for your replies! So, check this out: My MPG went from 12.5 to 15.6 on a mini road trip that I took up to Washington two days ago. I am wondering if this was due to the plugs getting tightened? This was my first trip more than the 3 short drives (15 minutes) that I've taken since this tune up. My trip was all freeway driving. Yesterday, I drove around town and the MPG is still high (for me), averaging 15.2. I am pretty darn ecstatic that my truck is getting such "high" gas mileage now. LOL!
Sadly, I cannot recall my Jeep have such great gas mileage! It has always been serviced at the deal(s). Last year is when the dealer changed the plugs. I notified them that my MPG had gone down. They said it was normal and would go back up. Well, it never did. It maxed at 13.1 MPG for the last year.
Big Blue: no, it's not lifted. Yes, I have after market tires. They are low profiles and larger than stock. I'm pretty sure they are 19" (I will measure and let you know).
2010 Inferno: The computer required upload of some software that the other dealer had failed to update, and then the 2nd dealer charged me. (wtf). This was done at the same time last year as the plugs, oil change, fuel filter change, and I believe air filter change. And then MPG went down. I have not tried resetting the gas mileage counter, but I'll try that and see if it's even better than the 15.2-15.6.