Rack Bushings for sure. MIGHT also be the LCA bushings.
If your a poor man like me, do this step by step.
Go to TMengineering.com and get the Daizen Rack Bushings ... $47 shipped to your door. Go to clublexus.com, and do a search, there is a thread with a step by step with pictures on how to change these yourself.
I did it, and it fixed my the misalignment in my steering wheel, as well as tightened up steering a lot.
If this does not totally fix the problem, then you need to get the LCA bushings as well. Shouldn't be too expensive. I do have a used, but good condition, lower control arm assembly for sale ... on the cheap.
Hope this helps.
Now if only someone could reply to my Power Steering thread, I'd be set! lol