I have a 2004 Ford Explorer with similiar but slightly different symptoms. As stated by other posters, the transmission is considered a “sealed” unit without a typical dipstick to check level or condition of fluid. I’ve just started trying to diagnose the problem myself because I don’t completely believe my issue is with the transmission itself. After some research, I disconnected the battery for 10-15 minutes, thereby clearing the Keep Alive Memory (KAM) and this temporarily cured my problems. It may be worth trying to see if this changes the behavior in your case.
In my case, the problem seems to be slowly returning (I suspect it is a bad torque converter) but at least it is one more piece of information I give when I take it in for proper diagnosis. Hope this helps.