what would cause steering to get harder to turn then go back to normaland repeat on 1994 Cadillac DeVille

In its easy to turn wheel with your finger by end of the day it takes both arms to turn the wheel the problem seems to be only around corners.The problem seems to get worse the more i drive it.When i let it sit for a few days the steering seems like new,I use my pinky to take turns.Power steering pump being replace 2 year ago.

Asked by for the 1994 Cadillac DeVille
1 answer 1 comment
Thanks i suspected that but what would be the factor of it getting worse and better.Is there a leak in a hose letting air in or the fluid is old and lost its properties.