do NOT NOT NOT NOT use bosch or autolites you will have a misfire within 3,000-5,000miles and your truck will run like crap ive tryed both of them and they misfired on me i put in motorcraft single plat.s like the book calls for and my truck has ran fine for 30,000miles.
i had a 99 F250 with a 4.6 it was fine for everything we used it for...man i miss that truck yeah the 4.6 is deff a dog in the F-250 but i belive you have 4.10 gears factory.
depending on how many miles are on the truck look into doing the coil packs MSD or motorcraft seem to do good accel coil packs have a bad rap on here i would advice not getting them.
also if its over 100,000 miles id do o2's as well. also has the tranny fluid and filter been changed also the front and rear diff oil. other than that i think you got it.