hi i have a 1997 buick regal gs 3.8 supercharged. the other day i was driving and it would almost redline before shifting out of 2nd and im pretty sure its shifting harder in all gears it also kicked out of overdrive a couple times to. If i let off the gas it will shift. I had the computer scanned and no codes. I also changed the fluid and filter and still the same. PLEASE HELP. any advice will be greatly appreciated.

Have you checked your throttle position sensor?

If the TPS was the cause of it, he would have a SES light for TPS issue.