What modifications have been made, if any? Bump steer is usually caused by lowering the vehicle, and/or installing a IFS system without doing some homework first. Assuming you still have a straight front axle, check to see if the drag link between the steering gear and the left front wheel is parallel to the ground. If it's not, the vehicle will dart side to side every time you hit a bump.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!