I bet you it the steering shaft joints. Spraying mine did nothing. I knew one was bad and hoped that would loosen it up for a couple weeks. It did not help. Tried several types of lube. It will probably take a while to get bad enough to be obnoxious. At first mine seemed to come and go. I checked all the things you did and decided to drive it until it broke for real so I could find the problem easier. At least it's an easy fix. Belt slipping would be most noticeable when parked not moving. More squeal and effort due to high traction and low RPM. Tie rods and ball joints would probably make a crack or pop noise when steering with it parked. CV joints would make clicking noise when turning at slow speeds like parking. Good luck.