I just bought Moog replacement rear springs for my 1994. They are shorter in size making them a little more easy to install but, are a more thick coil.
The ride is very good and my truck sits nice and level once again
Another option are the Old Man Emu rear coil springs. They will give you anywhere from a 2-3" lift depending on the ones you get. About $150 for a pair.
You can get the Old Man Emu springs straight off their web-site: www.oldmanemu.com the part number for a 1993 4runner would be OME900 for a medium strength coil, and OME901 for a heavy duty coil, ....., I would go with the medium. They charge $165 for a pair before shipping. May can find them at other vendors for $15-20 cheaper.