[99GSX]

Try a Transmission cooler, or even a lower temp thermostat (180). This may help your problem as it did in my Grandfathers 00 Century, but it only helped. My 99 Regal GS started doing the same thing, which progressed very quickly, what started as a stutter while going up an incline has now diminshed to a definate Trans problem. He used the cooler, I went with the thermostat. I slowed my problem, but I could have maybe prevented it by doing it earlier, I have 200,000 miles on my regal, the century only has 74,000. Either way the auto trannies GM gives us are not to be trusted. And realize you should be doing your trans fluid and filter like every 30,000 miles as the owners manual calls for. 99GSX "1Kwik6"