They're great trucks - I love mine. I don't know much about the 5.4 as it applies to the Ex - mine is the v10 and my last 5.4 was in my E150. If I remember correctly, though, the Excursion got the 2v 5.4 which is good and bad. The good part is no cam phasers. The bad part is that the early years were designed with only a few threads' worth of spark plug engagement. If the plugs pop out, use the Timesert kit for a permanent repair. If they haven't popped out, you want to make sure that they're torqued past the factory spec. IIRC, factory spec is something like 16 or 18 ft-lbs but internet wisdom says to take them to about 26-30 and they'll never blow out.
Buy an extra coil and a 1/4" drive ratchet with a 7mm socket. Put it in the glovebox. You will have a COP module die eventually. Make sure you have an ODB2 scanner that can read test $53 in order to see which cylinder is misfiring. Forscan also works for that. You can swap a coil out on the side of the road in about 10 minutes, so it's not a big deal as long as you've got one. A lot of folks say only ever use Motorcraft/Denso but I've had good luck so far with NKG as well as whatever O'Reilley's brand is. Masterpro? I don't remember, but it's been about 10k miles and no problems so far.
It is mostly F250 from the B-pillar forward. Heavy stuff, but pretty durable as a result and pretty easy to find parts. Manual hubs could be replacement or they could just be the stock ESOF hubs that have been capped off. The wheel seals leak and the vacuum pulse system stops working. If you have anything other than defrost on the HVAC system, then the lines have been appropriately capped off, but the first sign of a vacuum leak is usually that the air will only blow out the "fail-safe" position of the dash defroster vents.
The door lock actuators can be a pain. Don't buy the cheap ones from Rock Auto.
Steering can get wander-y as with most Ford trucks/vans of that era. A Cardone rebuilt box will work, the Red Head boxes are said to be worth the squeeze. Before you go that route, though, it's also common for the u-joints in the front axle to go out causing problems that seem like they're steering-related. Replacing those u-joints is something I want to do on mine and is probably a good time for me to also go ahead and replace the vacuum seals on my wheels and get my ESOF working again.
Tires are just stupid for these. Mine came with some A/T tires and while I guess they looked.... well, they looked like someone who liked the looks of A/T tires on a truck would like the look. But holy hell are they droney and noisy. I replaced them a couple months ago with a highway rib tire from Bridgestone for just under a grand and it is sooooo much quieter and smoother.
Oh, your exhaust manifold studs will rust and break causing exhaust leaks. It's a Ford thing.
Take the rear seat out, fold the middle row flat, and now you can quadruple the value of the vehicle by putting a 4x8 sheet of plywood in the back. Even with the rear seat up and occupied, the amount of cargo capacity in the rear is astounding. I had the tile place scoot a skid of ceramic tile in the back of mine. I was a bit overloaded, making the steering a little light, but otherwise it handled having the 2000+ pounds in the back without any real problems.
