Joe,
Transmission problems were very common in early model Sport Trac's.
The most common problem is the Shift Flare that you described. This can be caused by several problems...
1. Sticking valves in the valve body that causes the shift solenoids to act sluggish and often they wear out. The cure is to replace/repair the valve body and the offending shift solenoids.
2. The gasket between the two halves of the valve body is leaking and causing slipping and sloppy shifts. The cure is to replace the valve body gasket and insure that the bottom half of the valve body is absolutely flat before installing it with a new gasket.
These solutions will only work if they are done early and the excessive slipping has not worn the clutches and bands....If they clutches are warn to much, you will need a complete transmission rebuild.
As an added note, Some 2002-2003 Sport Tracs were recalled for Ford dealers to add a quart of Friction Modifier to the transmission fluid. They claim that a supplier delivered the wrong blend of Mercon-V transmission fluid to the Assembly plant in Louisville, KY. This recall only applied to specific Sport Tracs based on build date, and only if they had specific symptoms???
...Rich