I too have noticed in the last month a dramatic change in the ride. I have planned a number of suspension overhauls starting with the shocks.
If you want adjustables, look at Rancho RS9000X 9-way adjustables at
http://www.gorancho.com/. I have seen them on the Internet as low as $72 for my '93 Pfinder. Priced them locally as high as $125 each [mainly at tire centers]. But ended up buying them at a local 4x4 shop for $83 ea. The R5000 are standard non-adjustable shocks at a much lower price. Check out eBay for the OE adjustable shocks also.
And last, check out NissanPerformanceMag.com's Project Pathfinder at
http://www.nissanperformancemag.com/...pathfinder.php for suspension mods ideas. RC