Bumpsteer gets its name from just that…undesirable steering while going through bumps.
A good way to check bumpsteer is to set your race-ready car (including battery) on a completely flat surface and slowly press down on the front of the car. Does the angle of the front tires switch from toe-straight to toe-in or toe-out? If so, then you will experience Bumpsteer! This effect will cause the car to bounce back and forth through bumpy section of the track, instead of going straight.
Adding shims (or removing if there are already some in place) from under the steering knuckle ballstud will fix bumpsteer. You might have to experiment with the number of shims.