TL;DR below I have a 2013 P85+ and the last few months I noticed what felt like rear steering. When accelerating the rear end would shift sideways and the car would pull right. During regen it would shift the other way and pull left. My suspicion was rear toe links. There's not much that can make a car steer with the rear wheels and toe links are top of that short list. So I figured I'd just pop the toe links out and inspect the bushings. Unfortunately Tesla makes that impossible by mounting the inner bolt that holds the link to the sub frame front-to- back. You can't pull it out as it hits the body of the car. The service manual solution: drop sub frame for access. Thanks, Tesla. Not feeling the fun in dropping the whole sub frame I went for the simpler solution of cutting the bolt and inserting the new one from the rear where there is plenty of room. So after some inspection and research I found several things. My old toe link was PN 1021420-00-A. The service replacement is 1021420-00-B. The difference is that the end of the bushings have little bumps on them now so they lock in place to the frame brackets. The original design with smooth ends will move no matter how much you tighten the bolts as there is quite a bit of play between the eccentric washers (for adjustment) and the frame brackets. I don't know when Tesla updated the part but if your car is newer than my 2013 you may already have the B part. Here's what my old link looks like. Notice the center of the left bushing has a flat appearance. This is the outer end that has never moved. The right is the inner and you can see the abrasion damage from sliding back and forth. At this time I thought only the driver's side was moving so I bought one updated toe link 1021420-00-B and the eccentric bolt 2007061 from Tesla. Word of warning: Sellers on ebay want $120-$150 for used toe links but they're only $80 brand new from Tesla! The eccentric bolt was $8.80. As I had everything apart I also decided to fix the play between the eccentric and frame bracket by adding welds to the edge of the eccentric and then filing it down until it had a snug fit. This was surprisingly easy and quick to do. I put it back together and unfortunately it was better but not fixed. There was still a loose feeling to the rear. That meant the passenger side had the same problem. Before ordering another toe link and bolt I decided to just fix the slop in the eccentric by welding the edge. I could only do the rear eccentric as the bolt can't be removed without dropping the sub frame so that's all I did. Just got back from a test drive and it is now fixed. Rear end is perfectly stable. I'll drive it and see if it stays fixed. If it gets loose again I'll replace the passenger side toe link as well, but as of right now it seems fine. TL;DR: Problem is caused by slop in the adjustment eccentric bolt which allows the rear toe links to move. Updated toe link from Tesla ($80/side) fixes it. Alternatively you can weld the edge of the eccentric and file to fit to get rid of the slop instead of replacing the link.