I've read many stories about poor milage from owners till I seen what they did to their trucks!!!! If you did all that and didn't get the gearing corrected in the speedometer then your still having tire size issues. Its taking more revs of the trans to get the truck rolling, like staying in a lower gear longer. Every 100 pounds added to a car you lose 1 mpg, looks like you've added 400 pounds in just rubber and rims. The trunk is near 5000 pound to begin with so the 2.3 is not the best source of economy for a truck, I learned that my first month with my 2.3 XLT. I had a Grand Marquis with a 4.6 V-8 , it got 4 less miles per gallon (in the city) then the Ranger back when the $4.00 a gallon was going on. 4 bangers were meant for 1500 pound sub compacts with 5 speed manual transmission.
2007 XLT Super Cab 2.3 5 Speed Auto 2 WD