bumping and other noises

2004 Pontiac Grand Am; 91K miles; V6. I am hearing a bumping noise from the front of my car, when ever I go over a bump. It sounds like something is loose and is bouncing up and down. It also makes a sound that sounds like a very large spring compressing (sort of like a very deep squeek). There is also a very faint rattle. My mechanic has replaced the struts and mounts in the front twice. After the first set was installed, everytime I turned to the left, my steering column made a rubbing sound. My mechanic removed those and replace with Gabrial struts (not sure what the first brand was). The steering noise went away, but I still have the bumping and deep squeeking noise. It is not consistant.