We have a 99 Expedition, and I have to say its one of the most trouble free vehicles we have ever owned. We bought it a few years back with about 47,000 miles, it now has 180,000 miles, and still runs great. I certainly dont take really good care of our vehicles, we have run it out of oil and overheated it many times, and it still keeps going.
The biggest repair we have done to it is a new radiator (the cause of the overheating) other than that it has been minor crap like an alternator, starter relay and some minor vacuum leaks. Most all repairs have been less than $100 and an hour or so under the hood.
It has only in the past 3 months or so developed a leak, so its more than likely the front seal or the front differential, I really havent examined it closely.
My only real issue with the last gen Tundra was the fact that you sit so close to the windshield. When you are driving one it seems like you face is only about 12" from the windshield and its really disconcerting for me. Besides that everyone I have talked to that had one was really happy with it, and said it had a nice soft ride, not quite as choppy as a domestic truck.
EDIT:
Our Expedition has the 5.4 motor, but the engine really struggles to move the truck around. On ours I think it has more to do with the gearing and tires than the actual power output of the motor.
Ours has the 3.35 gears, and 32" tires which makes the motor really struggle on launch, but it excels at low RPM highway traveling.
If you do look for a 97-03 Ford try to find one with the 3.73 (most have 3.55, and some dogs have the 3.35) rear end gears, it hurts gas mileage a bit, but really improves the overall driveability.