Transmisson problems

I have a 1990 buick lesabre with 125K on it. My trans started to shudder when it shifted, so i took it in and had the fluid changed. The problem went away for awhile, but now its back again. Sometimes it shifts smooth, sometimes it shudders. I have no idea why this is happening. If someone could tell my why it's doing this and what i should do about it i would really appreciate it. thanks.

I am not positive but it could be the bands in your transmission. When the bands get loose you can get that shudder. To fix it you can simply have the bands tightened. It could be something else, but that is just my guess. I once had a car with the same problem and it was from having loose bands.