So, its a 2006 grand prix, trans was rebuilt about 60k ago.
Issues; Highway cruising, 4th gear locked up, you slightly feel a jitter, to me it feels like the converter is slightly locking up and then unlocking, seems really quick though. if you didn't pay attention you wouldnt feel it. Iv made several 800+ mile trips with it. and the rpms are not moving odd or anything. Also, every now and again, ill put it in gear, start to take off and it jumps, its only once in a while, (say once every week) and its been doing this for as long as i can remember.
Trans fluid could use changed, its got a slight brown tint to it, doesn't smell burnt though. I changed the fluid in it about 10k ago thinking it was causing this, it looked the same way......
Any thoughts?