I owned a '97 Expedition 2WD with the 4.6L for 6 years. Here's a list of repairs that mine had:
Pitman arm at 65k miles - $130 at independent repair shop
Transmission shifter solenoid at 75 miles - $440 at Ford Dealer
Rear axle seals around 110k miles - $175 at independent repair shop
Removed upper portion of intake manifold to clean EGR passages to clear CEL - $15 Parts - Repair done by me
The Expedition always consumed oil. I changed the PCV valve and grommet with Motorcraft parts around 100k miles, which decreased the amount of oil consumed. Keep an eye on the oil level, and keep it topped up.
Not sure what type coolant the '00 model F150 used, but it might be a good idea to change it. The coolant in my '97 was run way longer than it should have been (by me), and as a result clogged up my heater core. In late winter 2007, I paid a repair shop $75 to do a good flush of the lines, and re-fill with coolant. The heater worked OK from then until I sold it later that year.
All in all, I was happy with my Expedition, and I think you will find similar results with an F-150, assuming it hasn't been abused too badly.