My '99 still doesn't have any door cracks, that's an individual truck type thing.
The 4.6L has the least gripes of the available engines, relatively speaking.
I follow the maintenance guide in the owners manual.
Dealerships are all up and down the spectrum customer service wise.
Thought you weren't picking it up till Thursday?
Hit the rear rear slider hard with a water hose, both sides, along the top. Check for leaks inside.
('99 was the best year, IMHO)