I just bought a 2007 na grand prix. it has 138,000 miles on it. i didnt notice the problem when i test drove it bc the car never got to operating temp. today i actually drove it in town for a min without cutting it off and after about 10 to 15 minutes the trans started shifting hard from 1st to 2nd and from 2nd to 3rd. idk if its doin it in other gears but this is all i could tell. the fluid is where it should be. it seems like the transmission is holding too much pressure or something. i have a 30 day warranty on the motor and trans but i want to have an idea of what the problem is before i go to the lot and they try to bs me and tell me nothings wrong. i paid too much to have to get the trans rebuilt and it be me that has to pay. i dont even think they had the car checked out. i know the guy that owns it so maybe he'll be straight up with me. thanks for any help
