99 GA Sloppy Shifts - Tranny problem??

My 99 GA GT V6 has been developing a shifting problem. When I accelerate hard, it doesn't shift hard .. sort of like a slipping clutch would feel like on a manual tranny. However when I shift the gears on my own, it is not so sloppy. Do you think I have a transmission problem or a computer problem. Is there a way to adjust the shift points or how hard it shifts??

Thanks~ Joe

Check the vacuum modulator located on top of the transmission. It is inexpensive and not hard to change. You may want to pick up a chiltons or haynes manual on your car as it will show you exactly how to change it.

Can't be a vacuum modulator.. This is an electronic controlled trannsmission. I took it too a transmission repair place and they said that it stifted normal. If this is true, it is totally unacceptable. I have only had the car for a couple of months. Is there anyway to adjust the firmness of the shift inexpensively?? Thanks!

Yep, buy an aftermarket TCM (transmission control module). I believe the GT V6's have the 4T45E transaxle. They allow you to modify shift points, fluid pressure, etc. They run between 600-800 bucks US and on these trannies they give you the option of installing the ever so sought after "Paddle shifters" (which you have to make on your own cause non are available, but a good "2 button" momo steering wheel solves that).