Trans slipping on 1997 Mercury Sable

I have changed fluid and filter and added lucas trany additive and cured this problem before! But is their a problem with these trans I don't know about?

3 answers 2 comments
to tell you the truth you have been lucky at that mileage. seek a free diag and est from aamco then shop the prices
How many miles on it?
173000
might finally be worn out. Follow goodguy suggestion & get references for the shop you bring it to .
take it to tranny shop for diaqnosis