1999 C1500 Suburban "Catch" in front end

[bwood]

Boog is right on, the 99 burb has the steering sensor. The power steering system gives full power at low speeds but at higher speeds, it will cut the "power" steering back. It works with this sensor to decide how much to assist. The failing sensor gives a bad signal back to the system and it is giving you full assist in the curves. This is the jerk you feel.

You might also consider posting in the 88-98 truck section as you surburban shares the same powertrain, body parts as the 88-98 trucks. These trucks sometimes are called OBS (Old Body Style).