i have a 1998 f150, with a 4.6 V8. When i purchased it (used, about 4 months ago) i had it checked by a mechanic who is also a friend. it was given a clean bill of health, and had all the fluids changed. I added a K&N filter, and have kept the oil and oil filter changed on schedule. The car is stock.
I used to get 20 mpg with ambient temperatures 100+ in the day, at elevation 200'. I moved and now am at 10 mpg in 60 degree heat at sea level (and by the beach if it matters). My daily driving now requires a greater amount of idling commute time in traffic, but otherwise my habits are unchanged.
I have checked for obvious problems (tire pressure is nominal, air filter is clean, no pool of gas exists under my parked car, I have ruled out the siphoning of my gas, and I always check my emergency brake).
I have unhooked the battery cable in an attempt to reset the computer and change the driving profile, but I am thinking this will be fruitless.
Does anyone have any idea what might be wrong?
Thank you