Rear upper & lower control arm bushings need to be replaced.
This is a well-known problem with this generation Pathfinders... the rear upper and lower control arm bushings are worn. Have them replaced and the sway should disappear.
I had a 1990 nissan maxima that use to do that and the problem was my rack and pinion bushings were bad
Broken sway bar or sway bar links.
I had sway bar links replaced on my 2003 Ford Escape. Cost- $220 w/ labor. The parts are pretty cheap of course and easy to install; it's the "book" labor that jacks up the price.
I have a 98 infinite qx4 (from what I was told its just like a pathfinder) that was swaying/rocking. I changed the whole front end and some of the back. I even got different tires, but the whole time it was the bushings. If you're able to move the Controll arms side to side that's a bad sign. The arms should be firm.
Common problem with these 2000-04 fords, there is a sway bar link (approximately 12" long) which attaches the front strut to the sway bar mounted on the cars underside. The link ends wear and cause a "sloppy" connection between the two points. This is then herd while driving and hitting potholes as a "clunk". Just replace the sway bar link and everything will be fine!
Check the front sway bar and sway bar end links. I suspect one of the sway bar end links is broken. Auto parts stores carry the replacement link kits and are easy to replace.
The defective sway bar link can cause the clunking or the rattling of the noise from the front suspension during the low speed driving.
a clunk noise over bumps
If it's at high speed it could be alignment, loose steering components, bad tires, bad rear sway bar or overloaded in the rear of the truck bed. If it's at low speed it could be a bent wheel or slipped belt on one of the tires.
Here ya go: http://nissannut.com/projects/Poly_bushings/
I would guess sway bar bushings or strutts. what vehicle and constantly or only on bumps?