Thats funny, because i just bought a 90 something model as well, the one with 1kz, 3 door automatic.. except i think mine is too soft.. and in fact am changing the shocks and springs to make it hard!
Hard suspension handles much better in the Kutcha! On the road you may feel every bump but in the kutcha u wont feel a thing.
I have a Surf as well and it rides like a boat, which is fine for the road, but for off roading, such soft suspension is not suitable. I have Rancho 9000 adjustable shocks on it, and whenever i go off roading I change the settings on them to make it ride hard, even then its not hard enough and I will probably change the rear spring (front is arb springs) to arb and also make it dual shocks, so that there are 2 shocks on each corner.
You need to change your tires, and your springs.. and maybe even shocks. Buy Toyota stock springs and maybe even Toyota shocks or Monroe regular ones or the Adventure series shocks.
Hope this info helps.