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.