My 97 Expy 5.4 started the tapping/ticking noise about 10,000 miles ago. You guys all had good info on the piston slap, filters without anti-drainback valves and even the crankcase being low on oil.
Well I found that when the crankcase gets down only 1/2 a qt that the tick at startup lasts longer. If the crankcase is at the full line the tick is present for only 5 seconds or so. I think I still have a piston slap problem or something else but I never would have made the connection with oil being down only 1/2 qt until I read it here. I can't remember who mentioned it a few months back but thanks. Unfortunately she burns some oil at 103,000 miles but I check it now every week or so.
This site is better than a shop manual. Better than a Ford mechanic sometimes.