It not running ruff at idle or at speed . Some times it starts right up other times it goes almost to the end of the crank cycle someone told me that if you disconnect the battery you might have to go to FORD to get it reset ??
All of the above comments apply, but here's clue number 1:
"And if you stand on it it will set you back in the seat hard". My mileage drops drastically when I "put my foot in it" or when I loan a car to my son. But what good is horsepower if not to enjoy from time to time? BTW, you will not have to go to the dealer when you disconnect your batt, just give the ECM a little time to relearn your engine and transmission settings.
It's been a month and a half at 73 miles a day . Like I said when I stand on it it doesn't ask how Hi it just clears the moon. Jwk I believe you have loss in the colder weather also but not this much. If I am a good boy the milage is down 5
Do you have the means of measuring your fuel trim? You say it will sit you back into the seat, if it seems to be more aggressive, you may be burning richer. Not sure if it'd kill your gas mileage by that much, but it's a start.
if the cats are high flow, there may be your answer, reduce back-pressure will put a hit on mpg. i just removed some glass packs and returned the stock mufflers and gained from around 12 back to almost 18 from my 150k 4.6
also, a battery disconnect may trigger a re-cal that might correct your fuel trim map