What could be the cause of a rattling sound from the front end of a 2000 Lincoln LS?

It is your heat shield making the rattling , you can go to lube xpress are anywhere with a lift. They can take that off easily for you. Another rattling problem: My 2000 Ls sounded as if the front end was falling off when I hit small potholes or while driving on rough surfaces. I found that the front anti sway bar bushing was worn allowing movement. It wasn't noticeable by hand. The bushing are not available for replacement they come as part of the sway bar itself. I purchased one at a local Ford dealer for $125.00 It took 6 hours for me to replace it and had to pull it out from the drive side wheel well. It was very cumbersome to do but it eliminated the rattling completely.