i have a 01 e350 with 5.4, and i changed out the passenger side in about 1 1/2 hours. did the drivers side in about forty five minutes. used an eight inch straight extension, ratchet, and 5/8 sparkplug socket. i have read others had to have a universal joint, but i didn't. i pulled the pcv and line, the four screws holding fuel rails to intake, air intake horn, and of course each individual coil. the last two on drivers side i had to wiggle coil out, but the extension slide right passed the fuel lines when you pull the plug. i recommend lots of dielectric grease for the boots, and plenty of anti seize for the threads. most of all do it while engine is stone COLD. otherwise stripped threads may happen. torque them no more than 12 ft lbs. it's hard to fit a torque wrench in there so i torqued one and felt the rest out. also i did 5 of them from inside the van.
Can't stress enough the use of a nickel-based anti-seize and proper torque---if a socket and extension fits then a torque wrench will fit as well. I bought one graduated in inch/pounds and Newton/meters 3/8 drive and no problem fitting it in where needed.
I'll add its been written here Motorcraft plugs are preferred because their threads are complementary to the Ford heads---I myself use nothing else.
First time out its a pain in the butt----next time you're better prepared and can allot the necessary amount of time.
Its interesting that bit about letting the dealer or other mechanic do it, that way it becomes their problem----probably very much NOT the case! Since it's a common problem and if the engine is out of warranty---you'd get charged for it I'd bet.
I'll also share during a conversation with the local dealer parts guy he tells me their mechanics never use anti-seize and never have problems--???? Even if only half true that's scary about a dealer!!
I don't know for certain but I'm told its up to $400 for just plugs alone. Add in everything else they'd find wrong it could approach even more. Given I myself don't trust their mechanics and these motors anyway I'd learn to do it myself---possibly with the help of someone whose already done it.