00 Lesabre - rattling sound - rt front

I am meticulous in maintaining this car. This is my third LeSabre. So far, nobody, including Mr. Good wrench, can figure out what it is. I hope someone out there might have some idea.

It sounds like a low, intermittant rattling noice coming from the passenger side front wheel area. One mechanic thought it was something in the dash. It almost sounds hollow, like air rushing through a plastic tube, but its a rattle. The sound doesn't change as speed increases or decreases. The sound seems to almost go away on very smooth pavement or when coasting, any speed, not applying the gas. I have ruled out a bearing, its not an intermittant metal rubbing on metal sound. I don't think its the timing chain, the sound goes away when the car is not moving. I have removed the heat plate over the cat. Engine and transmission mounts were checked when the solonoid was replaced and they're ok. I have new tires, new rotors, pads. I replaced the solenoid two months ago. I had a 94 LeSabre. When I traded it, the dealer told me it needed a new transaxle. This sound is similar. I was driving a brand new Bonneville, rental, a few months back, it made the same noice only less noticeable.

Would a bearing make this kind of noise as it begins to fail? Could it be a strut mount? any other ideas? Many thanks.