Carrier/rack problems of the 2011 Ford F-250

Was getting on the interstate and went over a separation crack at about 55 mph when the truck front axle / suspension started to vibrate violently / shaking uncontrollably. I started to put a secure hold on the steering wheel and at the same time applying the brakes. After slowing down to about 35 mph the truck started to smooth out, pulled over to the side of the expressway, checked the truck out, did not find any problem. I continued at reduced speed to home and checked it out again, but did not find anything. Prior to that incident, I had complained to the dealer about what I thought was a rough ride, went with a mechanic from the dealership for a ride, and he said it rides like the other f250's. After the vibration incident, I decided to check the left front shock, removed it and thought that it was not working to well. Took it to the dealership and they said it was a little bad, and they would replace it, I then ask them about the right shock, and they did not think that the right side was bad, I then stated that I was told that they are replaced in pairs, and that the rears should also be replaced. They said no, but after more discussion, they did agree to replace the right shock {customer satisfaction}. It did seem to ride better. How ever on the evening of Friday 7 August, the truck had another episode on a different road, like it had over a month ago. So I don't think that shocks are the total problem. . It is possible that under different weather conditions, this problem could injure or kill many people!!! so who is to blame ???? not me !!! . ,.