I have that same problem that I have been trying to get rid of for almost a year. I replaced the struts and springs and also put in a ITR sway bar and nothing would make the sound go away. I have it on the passenger side in the back. I figure it might be the trailing arm bushings because they look pretty rotted but I don't want to replace them myself because I've heard they are a bitch. I don't really want to pay out the ass for someone else to replace them either because, frankly, it doesn't bother me that much.