Steering issue

[saginaw]

First, sorry for my bad English. I have a 71 Suburban 4x4 that i drive all the time, its lifted 6 inches with 35's. Ive never had any problems with it earlier but from about a year ago something started to happen with the steering and now i dont dare to drive. Steering is under normal conditions fine, but out of nowhere i loose steering when turning, if i turn and turn finally it works but when turning back nothing happens until Everything comes in a second and im all over the road and sometimes it just steers by itself to the right. There is no play in the steering box, all rods are fine etc. Could the steering box be the problem although most of the time it works excellent? Btw after it did like this today and i stopped i couldnt rotate Wheels to the right but all of a sudden it worked again.