I've got a 96 GXE. It's my wife's car, so I only drive it occasionally. Recently I noticed that, at freeway speeds, the transmission would kick down a gear when going up just a slight grade, then drop back, then kick down, etc. The RPM jumps to nearly 3500, so it might even be dropping into passing gear.
There was no indication of the engine lugging. I thought maybe it wasn't getting enough gas, so I changed the fuel filter. That seemed to fix it, but I drove it again recently and it's back. (I didn't really think it was going to be that simple, but it was time to change it anyway.)
It doesn't seem like it's lost power, so I suspect it's something in the transmission. My knowledge of transmissions is pretty limited, though. I thought there might be a leak in the vacuum line or the modulator, but it doesn't look like those concepts mean anything any more...
Any one know what the problem might be?