My 2.5L got 23.3 mpg today @ my fill up, mixed driving!
You bought a 3.0; it's a motor that was used for the Taurus. The 3.0 is a car motor, not a truck motor. You bought a low displacement v6; if you want gas mileage, swap to a 4-banger.
For what it's worth, my 1989 Taurus with the same 3.0 got 25mpg highway. Truck has more wind resistance and is heavier. Your mileage is normal.
Plussss... You have 130k miles on the motor. I'm sure you've lost a MPG or two over the past 14 years.