I'm going to mention again the loose fitting because it offers an explanation of the problem, and checking a few nuts is so trivial an effort.


The power steering is a closed system. The pump pressurizes the fluid on one side, and accepts less pressurized fluid on the other. If the less pressurized side has a leak, it will suck air into the system, and quite possibly pressurize it in the process of pressurizing the high pressure side. I would think at some point this could maybe cause your "vomiting" problem.