01 Mercury Sable Clunk in front end

My 2001 Mercury Sable w/ 100000 mi recently started making a clunking noise coming from the front end. The clunk is most noticable at lower speeds on rough roads. It sounds as if something is loose in the left front. I have had outer tie rods replaced, all ball joints, and bushings were said to be ok. I have no real answer, and the noise seems to be getting worse. I get answers like we can try this or try that. But would like to be a little more definate before just swapping parts. Please Help!