I have an 05 Expedition with the same engine as yours with around 90,000 miles on it. I also have an 02 F150 with 140,000 miles with all the original parts and still running like a champ. The expedition has had one problem after another and it still needs a ton of work. Right now it has a vacume leak that causes the AC to shut down while accelerating a year after I paid $1,500 to replace an AC hose, ball and U- joints need replacing, I paid over $2,000 to fix the transfer case last year and it's having problems again, and it has a front wheel bearing going out.
Sometime between 2002 and 2005 Ford decided to go from making one of the best trucks to pieces of shit. Oh and the Expedition cost $60,000 when I bought it new compared to $28,000 for the F150. I'm glad you've had great luck with your 250 but I doubt if I'll ever buy another Ford product. For the amount of money I've dumped into the Expedition I could have a couple classic trucks completely restored and with a new engine put in every few years, and I could actually work on them myself. I look under the hood of a newer vehicle and don't know what the hell I'm looking at.