Possibly some sticking solenoids in the valve body causing to not fill the
clutch packs quick enough? How many miles you got on this thing? Some more
info would be helpful. Are we lookin at a 2WD, 4WD, or AWD explorer?

I would start by checking your fluid level in the tranny, and looking at its
color. It should be a nice warm reddish pink color. Sounds like its possible
you dont have enough fluid and the torque converter is running low.

You could try disconnecting the negative battery cable for a few minutes to
reset the computers onboard. That will erase all of the adaptive strategy
for the tranny and require it to relearn all the shift points again. I have
heard that if you dont take a vehicle out on the highway very often and just
drive around town, it will cause it to shift very poorly.

So let us know how you drive, what kind of Explorer we are dealing with and
engine size and such and we will see what we can figure out..

Ford Tech