I recently bought a 2003 S-Type R with the same transmission and the problem occurs to me as well. Have 147k km on it, the transmission shifts well, no issues overall, just this annoying hunting when doing 70-90km/h on 4/5/6 gear. As the car is more "sporty" I would like to get rid of the problem. Some say that the problem is within the valvebody - solenoid number 6 (the lockup solenoid) does not fully engage so there is indeed a slip within the torque convertor and that's not what You want when accelerating hard - the lockup clutch is stressed too much. In my country, there is a service of rebuilding the torque convertor but that means somehow removing the transmission and I'm definitely worried about that. Did anyone of You guys found a solution? Tomas.

 

I have this same problem. I just live with it, I hope it doesn't fail on me but I would think many people have this problem and as of yet I haven't read of a failure of a transmission due to this "feature"?