Question about VSS problems

The wife's 97 Taurus Wagon, standard 3.0 engine not the fancy one, 97000 miles, has an interresting habit when cold starting of taking off in 1st,
winding up to about the shift point then putting itself into neutral. She says that if she holds RPM to 4300 it will eventually catch as the speed begins to slow down, but if she lifts off the gas, she needs to come almost to a complete stop before the next gear catches. The thing does this through all forward gears, until about the start of the 3rd mile of driving. Should I be looking elsewhere, or is this probably a problem with the VSS? I know that was a discussion happening earlier in the group, but at that time I was more interrested in following the threads about the BOO switch/trans lock issue that we were having with the 95 Tracer, and I haven't had much luck doing searches for prior threads.
Also, any tips for what maint we should plan for the trans? To the best of our knowledge it is due for the 2nd or 3rd trans fluid service, but we got it used and don't know if anything has been done before. Will we do more damage by changing fluid & filter if not done previously or is the benefit better than the risk?
Thanks in advance,
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