-98 explorer leaning left

I suddenly saw that my -98 explorer are leaning left when parked on level gorund!
A few times i have heard a rattling sound from left rear somwhere around the wheel.
It is equipped with auto ride control, i believe, as there is a switch to turn it off when jacking it.
I don't know how that works, and haynes does not describe that enough.

Also (i bought it a few months ago) i think is has a quite stiff ride in general. Of course, it's a SUV. But anyway some connection to my leaning problem?

Please help!

Martin/