One problem related to steering gear box shaft pitman has been reported for the 1999 Chevrolet Suburban. The most recently reported issues are listed below.
While driving slowly or fast, at different times, and not every single time, turning to the right around a curve or turning a corner the steering holds the turn and then all of a sudden lets go of that hold. I can correct it by slightly turning the steering wheel left and then back into the turn. Sometimes it holds the second time and sometimes it lets go again. This is repeated until the end of the curve or turn. Steering gear, pitman arm, steering pump all replaced and problem still is present.