picked up a 95 F150 up here in Wyoming (stuck working up here for 90+ days), it's the inline 6, auto, 4x4, longbed, standard cab. very clean, straight truck that blows ice cold AC. already replaced plugs, wires, and air filter...as the truck mostly sat - it's only got 116k on the clock, lol.

does it have 1 or 2 O2 sensors?

1 or 2 fuel filters/pumps? (since it has the dual gas tanks)

it's running good so far, just looking to add some mpgs, as right now it's about 12.5 combined city/hiway...thanks.

 

One oxygen sensor. One filter. Two pumps, one in each tank.

 

My 92 4x2 F150 work truck had the 300, automatic OD, 3.08 gears, and 235/75/15s. It was mostly a site truck and it was pretty beat when I got it. On the open road it would get 16 mpg. Most of time mileage was 12 to 13 with the truck rarely getting into OD.
Among our fleet of trucks it got better gas mileage than the 05 4x4 4.0 Ranger, 99 4x4 F150 4.6 SC, 04 E150 4.6, and got the same as 00 Dodge 1500 4x2 with the 3.9. Only the 88 4.3 Chevy 1500 did better on gas by a small amount.
My personal 4x2 F150s with the 300 and 5 speeds would get 16 to 20 mpg. The 94 Rc Sb had 3.55s and my 95 Sc Sb has 3.08s. The 95 is in better mechanical condition than the 94 was and gets the same gas mileage and performs better.
You were wise to change the usual tune up items. I did upgrade to spirial core low resistance wires.


Stock timing is 10 deg BTDC My ignition timing is set @ 12 deg BTDC

I pull, clean, and gap my plugs to .050 once a year. Th stock gap is .044.

The 235/75/15R tires are aired up to 38 Psi

There is a dash mounted vacuum gauge that helps determine engine load and has been on all of my rides for the last 25 years.

Many times the plastic chin spoiler is damaged or missing. Its worth about 1.5 mpg above 50 mph and helps engine cooling.

On my automatics I always switched to synthetic and added an aux cooler, mostly to help the tranny live but both my 700R4 and AOD picked up 1-2 mpg.

I calculate my gas mileage at every fill up and I do try to save gas. Most of my co workers newer 4x4 V8s average 2 to 4 mpg less but most are guessing.

Pull your codes, even if the CEL is off.

I commute 20 miles each way into Boston ( 5 miles city driving) and average 16.3 to 17.7 mpg in the summer and about 1 mpg less on the winter blend gas.

YMMV
rikard