It depends on if it's been done before. I'd think by now it had. They were warrantying them past 100k I believe, but I think you are out on time by now. How many miles are on it?
check for the recall, have the vin and call toyota
I had the same problem on a 90 4runner, if it hasn't been done yet it's under recall from toyota. They fixed mine at 215k no cost. I went ahead and did all the belts, wp, cam and crank seals, tensioners, and a knock sensor while they were in there (about $600 out of my pocket) since they had to take it apart anyway.