I have a 98 4runner sr5 with 90k on it. All stock with new tires until I started experiencing the very same shudders over small bumps. Especially when going over them at low speeds. I replaced the steering rack thinking that might have been it. Then I replaced the lower left control arm(seems to be the side of shuddering). Am thinking of putting Bilsteins on because I am at the end of my rope. Please let me know if anything you find works. I feels like its unsafe as well.