One problem related to rear suspension springs has been reported for the 1997 Toyota 4Runner. The most recently reported issues are listed below.
Purchased a used 1997 4-runner with CA. 258000 miles early in 2020. Engine and whole body was good. However, 6 month later the car started to shake violently in the rear at highway speeds swinging like a boat, which I though was due to a broken shock, springs were newly installed in 2020. I noticed that rear stabilizer arm on passenger side had broken off due to rust. When driving to repair shop the car rear axle broke loose, shifted, and the rear drive shaft fell out - I could pull over in 4 wheel drive mode. Please know that the rust an extensive frame rot on the the rear frame on both sides was not very visible from outside. Repairs for frame weld were 2500 -3000 usd. The 1997 4-runner, v6 is a very unsafe vehicle to drive!.