I had the same issue for like 2 years. I changed my pump but the droning noise wouldn't stop. I was told I'd need to change my steering rack. Turns out it was just a bad o ring in the hose that goes from the power steering reservoir to the top of the power steering pump. You'll need to remove the airbox and a t27 star drive to remove the hose. Hope it helps.

 

Did you flush out old atf fluid and add new fluid

 

I just poured out the fluid from the reservoir and topped it off with new fluid

 

I would turkey baster remove the fluid a few more times like once a week for next 2-3 weeks

 

Did you do it with the pump still on the car, was fluid coming out, and was there air in the system afterwards?