there is a kickdown band adjustment that can be done at any automatic workshop (someone who knows fords )
and a service oil change and filter would be a good idea
the transmission control tcu or
ecu or the icu unit may be faulty
undo the battery teminals for 10 minites this may reset your computers
if nothing changes you may need a diagnostic of those units
wont be a line pressure problem as you have all the gears