Steering jerk to the left when braking?

Short version:
My Beast jerks hard to the left while braking. This has happened twice. The first time, I skidded into a retaining wall. The second time, I nearly caused a head on collision.

Long version:
Shortly after I got it running again after it sat for two years, I was coming off the interstate and pressed the brakes. The steering wheel immediately jerked to the left, which sent me into a skid that ended when I hit the retaining wall. The impact damaged my bumper and front quarter panel and broke out the headlight. Because we had just finished working on the brakes, all the guys assumed that it was because of the new brakes and me not being used to driving a V8. However, I know what I felt.

The second time this happened, I was on a two-lane road in the car in front of me, started to slow down. I hit my brakes, and my steering wheel turns sharply to the left. Had I not jerked it back, I would have been in a head-on collision, or I would have rolled it because I was going too fast to turn that hard. When I straightened out, the steering wheel went from being perfectly aligned, to it sitting to the right at about 3:00. The steering felt off for the next 15 minutes or so, but then I hit a large bump, and the steering wheel alignment corrected itself.

Any ideas what could cause the jerk?