Need help choosing correct FICM flash and ECM Rollback

[FordTough04]

Im sure you get this same question all the time, so sorry in advance. I have a 2004 F250 6.0 automatic that at one time got decent gas mileage and out of nowhere dipped. I tried everythnig under the sun to figure out how it happened and realized my wife took the truck to the dealer without me knowing and they must have flashed my ecm. The engine is non-studded and non-tuned. On the FICM I was wondering what the best tune would be for fuel mileage? Ive read some on here say Atlas 40 and some Atlas 80; Can the Atlas 80 be applied safely to a non-studded vehicle? As far as the ECM I know for sure I want the rollback but as far as the custom tunes, would the 65 or 80 Daily Driver be sufficient or do you reccomend another? Also as far as the EGR part of it I dont have the delete as of now but plan on one in the future, by including that option in the tune would the vehicle run fine and just turn the EGR and light off or is it essential to have the delete in place before the tune is implemented. My truck is used for hauling my boat on occasion but otherwise soley around town and highway driving so fuel mileage is priority number one. I also have the Fuel pressure/EGT/Boost gauges to monitor any of the going on's. Sorry for the massive questions, but as soon as I figure out the game plan Ill be ordering the tuner for sure