'97 Cutlass Supreme Code P1870

Hey all. Just a quick question here. I have a 1997 Olds Cutlass Supreme,
with the 3100 V6 engine. It has around 201,000 KM's on it, and usually runs
like a top. I am in Ontario, Canada, so when I bought the car 2 or so months
ago it had to pass an Emission's Test. This it did quite well (though it was
a dealer who did the Emission Test, not myself). A few weeks ago, the 'Check
Engine' light came on. I had it scanned and it came up as an Oxygen sensor
code (P0134). No other codes were coming up. I replaced the Oxygen sensor,
and after a day or so of driving, the code 'Check Engine' light went off.
However, I was still a little worried, so I had the car scanned for codes
again. This time it came up with the Oxygen Sensor code (P0134) as well as a
P1021 and a P1870. I cleared all the codes at that time, and checked
yesterday and the only code that has remained (I have put several hundred
KM's of highway and city driving on the car since I cleared the codes) is
the P1870 code. From what I can tell, a P1870 is a "Transmission Component
Slipping" code. I have noticed that at times when you accelerate it seems as
though the car does not have power for a split second, then it gets it back
and you take off. Other then that, the car is running perfect, and seems to
be great on gas for a 3100.
I was wondering if anyone had any suggestions as to what this may be? Is it
usually something inside the transmission where it would have to be taken
apart and looked at, or could it be some form of sensor that is
malfunctioning? Also, would a transmission fluid and filter change make any
difference? I know it can't hurt, but if the transmission is going to need
serious repairs, I am getting rid of the car before spending any more money
on it.

Thanks all for any help you can give me.