weird problem need help please

When driving my car fast around corners my dsc light will flash and i will feel a weird knock from my steering and sometimes vibrations. The wheels are not slipping, it just seems like the system will randomly panic in the middle of a tight corner. This problem seems to have started after installing my zhp steering rack. My mechanic says that my steering column bearing has some play in it and I don't know if this related to the problem I'm having. I hear a knocking noise coming from the front right side of the car while driving over some bumps and my steering wheel has a slight shake about 60% of the time at speeds over about 55 mph. Tonight while driving about 70 mph I hit the brakes and heard something bang and then a hissing noise followed that would fade in and out. The hissing noise seemed to happen after braking but I'm not certain of this. What stumps me is that I have replaced EVERYTHING on the front of my car. meyle control arms, new zhp rack, tire rods, struts and mounts, springs, sway bar and bushings, end links, coupler you name it (except the steering column). My car just doesn't feel right and I scratch my head every time i crawl under it trying to find the issue. Can anybody give me a clue? FYI- I didn't have my car aligned after the steering rack swap but the car does drive pretty straight. Any help would be greatly appreciated. Thank you