Front end jumping while in reverse with the wheels turned all the way

When I am in reverse with the wheels turned all the way, there is a repeating jump in the front end and a soft knock that goes with it. It is getting worse, but does not always happen. Also, I have an EGR light that continues to go on and off. everything in the system has been replaced by the dealership that had to do with the EGR including the cars computer, catalytic converter, she valve etc., the light can go on or off after a hard bump sometimes. Thank you for being auto rescue angels.