I have 'loose steerig" at higher speeds ! It is unsafe feeling! Why is that?

You could have some lose parts in the steering and or a bad power steering pump. At high speeds the pump is working faster and if the pump is weak it would cause some of the same problems. I would want to look at your front end as well.

It could loose steering and/or suspension parts,and/or mis alignment. also check for correct tires and wheels size /air pressure.To properly diagnose these items should be checked both front and rear. ED ED HALEYS REPAIR