We've had our '90 LS400 for about 3 months. It has 212K on it and very clean. Co-worker had it for 12 years and all records kept. Car drove perfectly smooth until about 2 weeks ago when we lent it to our daughter for a day. She never mentioned anything happening, but I now notice a bit of vibe and slight shake on the highway around 60-70. Took it in for re-balace/rotate, and alignment 2 days ago.
Tech said alignment was out "quite a bit" but now in spec, so I thought that would have solved it, but it has not. Inspection/rotation did not indicate any bent wheels, worn parts, etc. These tire shops make their living finding things to replace, so if suspension/steering parts were bad, I'm sure they would have made me aware.
No unusual sounds at all and the trans shifts fine. Any ideas where to look next? Thanks in advance.