Sidekicks/Trackers have always had IFS since they came out in 89. The Samurai is the SAS rig you are thinking of. Look at OME Struts for the front. It will make a huge difference in the ride. Also make sure you are running the VEHICLES recommended tire pressure (not the pressure listed on the tire). These things are light, and 35 psi on a tire will make it ride like a tank. I have heard that the OME springs offer a better ride, but I have never used them.
HTH,
Zig