your transmission shouldnt be lazy, infact, ive owned my expedition long enough to personally know that its almost impossible to kill this vehicle. for an original owner with hardly 100k, the only thing "lazy" sounding here is you!
lol with that being said, you should definitely look into replacing the throttle position sensor, yes, this little 30$ component handles all the shifting, among other things, and is very fragile and prone to heat damage. i have an entire thread on this, just search for "the dreaded throttle position sensor".
first time changing it is tough because the bolts are really stuck, best to just remove the entire throttle body (only 5 additional minutes of work)
as for your engine,
these things go into limp mode when the temp rises, it seems difficult to really damage these engines.
tell us how you overheated your engine, dont be afraid to sound like a total fool, nobody here personally knows you!
i must also agree with looking into the exhaust manifold. the ticking will sound 100% like a valvetrain issue even though its not. your engine is built extremely well, it has many things you simply cannot find stock today, without going aftermarket. such as a forged crank, and other forged components. if you really want to just throw that sweet low milage 5.4 away, i would be more than willing to help you! where by chance do you happen to be located?