The 3.0 behind an auto is terrible, especially when in a Runner. Since you have to keep the auto your only option for real power gains is to regear. Since it is likely that your Runner came w/4.56's for the stock 28's, you would want to regear to 5.29's for the 32's. The 4.88's mentioned above wouldn't be the proper gear set for you since they are the oem size for 31's w/an auto.

Other options would be to open up the exhaust, yu can do it cheaply if you don't install headers, headers will run about $700+ labor(if you don't install them yourself). I have achieved good results from an ignition upgrade combined w/my custom fab'd cold air intake, electric fan, along w/headers and exhaust. I figure I have spent about $2k in engine mod's over the years and have a nice solid power band even w/my truck weighing 4600lbs before loaded w/gear and passengers, though my mod's are w/a 5-sp and not an auto.

However before doing any gear or engine mod's you will want to make sure that the engine is running correctly, 3.0's tend to burn exhaust valves.

Engine swaps like the 4.3 Vortec or the 3.4 Toyota engine are popular but also pricey, figure in the neighborhood of $4-5k.

Your other option since you need to have a rig w/an auto would be to sell the '92 and pick up a 3rd gen Runner('96-2000) w/the 3.4 already in it. Some models came w/factory electric locker. You could probably find one for what you would get from selling your '92 and what you would to pay for gears and engine mod's. Here in CA clean 3rd gens are selling for $6-11k, so they should be cheaper outside the state as most Toy 4x's are.