Im new here and just bought a 1999 S80 with a 2.9 ( non turbo) love the car veey much and am having a problem. 40 threw 60 at a steady speed the carrocks front to back and the rpm gauge bounces about 200 rpm. I use 91 octain and have spent over 4 hrs reading posts about the etm being bad. Is this possably my problem. Car shifts perfect and dosent make any other noise or shake at all it has 133k on it.

 

Maybe the torque converter but I'm just guessing.