So I have the same problem with a 01 LS430 with the Ultra package (109,000 miles). Lucky me I just spent $4,500 on 3 new air struts. I am getting the groaning when I brake hard but I also have a lot of movement in the front end when I hit a bump. It feels loose and makes noise. Any advice on what I should start replacing. When the dealership replaced the air struts they indicated that I needed new lower control arms. I would like to avoid that expense if I can try replacing other parts. Any advice would be appreciated.