Rich, for the 2000 EBs, ask when the last plug change was done (should have been at 100K miles). But, if the plugs were recently done, then you stand a chance of a plug blowout (only 3 threads holding the plug in an aluminum head and if the plugs are overtightened or not tightened enough, the plug will loosen up and eject out of the block, unfortunately, this is true of all 5.4L blocks from 97-03). After that, listen for a clunking from the rear end when hitting bumps (lower shock mounts become loose when non-ford shocks are used, requires the addition of a fender washer or a custom metal sleeve inside the shock mount that is 1/8" longer than the sleeve that comes with the shocks). Beyond that, a lot of the problems that you are going to see are just due to the age of the truck.
If you are looking at going slightly older, I am selling my 97. It has a 4" lift and 37" tires on it already and the plug issue is already taken care of (Timesert'ed all 8 cylinders, upgrading the holes to 6 threads with an aluminum alloy sleeve). I have a lot of other goodies in the truck. Too much to list here. I only have 130K on the truck.