Power Steering and BMW H31 hydroboost whoas

All,

I have the BMW Hydroboost system. It seems to not work properly. Trying to figure out whether or not it's the pump pressure or something else in the system. The brakes seem to work fine however the steering only seems to assist whenever I am on the throttle. And there is also a constant whining. I tried to bleed the system for months now and they're still seems to be bubbles in the reservoir tank. So I'm not sure if there's air getting into the line somewhere or the pump itself isn't working or there's an issue with the BMW parts from the H31. I have even thought about if I have my system connected properly if it's feeding accurately. When disconnecting the low pressure lines running from the accumulator they seem to be dry like nothing's running through them I'm not a hundred percent sure that. But that would make sense in that the steering does work whenever there is constant revs from the engine. Even though it's making a lot of noise. I thought about going to a higher pressure power steering pump from like the Cadillac. It supposed to have a higher pressure than the current one that I have which is from a Camaro LS1 5.7 l. what I understand is that the rack needs about 1700 to 1800 PSI. And that the current pump puts out about 1300. The Cadillac pump will do upwards to 1700.

I've even looked at trying to get an electric pump from an MR2 and try to get it fitted however I'm not sure if that would even meet the necessary PSI requirements.

Any thoughts