I just bought a 2002 with a 4.6, with 200k miles, in surprisingly good condition, my bodyman bud told me they're the best Ford products out there for corrosion resistance. I have corrosion in the door bottoms, an easy fix, which will happen tomorrow, as I am not driving it this week, due to a CEL for EGR, which via the web, I have ordered a DPFE sensor for, apparently, one doesn't change the EGR valve immediately for low flow EGR OBD2 codes, the most common item is that DPFE deal. good ! It looks like I could've been in for a nightmare if the EGR valve had to come out, as the rusty steel bolts are cranked into aluminum, (do I hear galled threads, anyone?) the tube is rough looking, too. The spark plugs are to be treated kindly, apparently, as they're screwed into aluminum, as well, and only about 4 threads - worth, I may put them in with a nut - driver, if I ever have to change them. What I found today, though, bothers me, and you may find it worth looking into. I pulled the cover off the engine, and started pulling connectors, and every one of them was corroded at the contacts, I scraped every connector under there, and dielectric greased every one of them and plugged them all back in. there's formed hoses, as well, that you may be wise to replace, everything from alternator connections to the injector and coil plugs, some single gray ones at the front of the heads, I was very surprised at the corrosion, because the 1st impression of beneath the hood, looked so good. I really believe I saved myself from a walk this winter, today. One other thing, that EGR code also gave me a low RPM miss on #1  cylinders, something I will report back on, when I get the DPFE sensor. It ran great when cold, not so much when warmed up.
