I am not sure these are related issues. However, if they are then I can only assume you have a power steering pump issue. I attached the process for replacing the pump as I suspect the low speed maneuvering is what is pushing the fluid out of the pump.
However, the high speed vibration could just be as simple as a steering damper or tire issue. The damper is located on the front of the suspension. Clearly the most likely cause of vibration at higher speeds is a loose suspension component but if you are saying they are all tight then the next likely cause would be the damper. Let me know if there is more detail that could help but I would suggest starting with testing the power steering pressure and going from there.
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Sunday, July 26th, 2020 AT 5:22 AM