I have an Str 2003 with 125 000k. Bought it about 2 months ago. The car was shifting harsh on 1-2. 2-3. 3-4. Its shift fast with an extra 150-200 rpm bump just before upshifting. From 2-1 there a knock kind of a sound and from 20km/h to 10km/h there a constant turning grind sound (like if it was the drive shadt) Only on drive ! But if I shift to neutral while driving between 20-10km/h the sound goes away (on neutral !)

Changed the oil and oil pan filter. Reprogrammed the whole thing at the dealer (ecu, trans computer and blabla). Drove it like a grand pa for 2-4 days to let it relearn between 1200 rpm to 1400 rpm max. Still harsh ! Never had any transmission fault code or check engine or restricted performance (well only once for about a minute). I have a check engine but its only the pcm valve. Need help !

 

First fix known faults. It'll learn badly until you do.