Marco had asked me to provide updates on my mileage since I changed the IAT. After cruising up to Northeast Georgia for the 4th, on my return home my trip computer was showing a steady 21. 6 mpg (average of last 30 gallons used). My normal was 21. 4. The 21. 6 is a combination of Interstate (20%), 2 lane and day to day commute driving. I have noticed that even with the summer heat, my EGT at cruise is about 50*F cooler.
That may or not be related as much to the IAT as I would like to think because it has been raining here every day and I'm sure the humidity plays into the equation somehow. Also, I changed my lift pump last weekend and that may have provided some of the boost in mileage. It definitely provided a boost in performance. I do believe that the IAT is a contributor to the slight mileage increase.
BTW, my trucks computer is now very close displaying what I calculate. I normally just calculate on a mpg and don't try to do the last 30 gallons versus mileage. So in certain driving conditions, I'll get 22 plus based on gallons since last fillup (calculated). I'm curious now because I may approach 23 mpg in certain situations (60 mph on the two lanes).