hi im having the exact same problem with my car only its when im at speeds 50 or above and hit the brakes. im still trying to figure out what it is. i talked to someone at a toyota service center today who told me it might be the caliper going out on that side. the abs light hasnt come on and he told me if it was a problem with that the light would be on. im hoping its just the caliper so i can replace those and get it working again. i just had the engine rebuilt and cant even drive it on the highway
hope you get yours fixed soon. i know what it feels like.