99 Tahoe Steering Slips when turning right

WHen I turn, sometimes even just slightly, to the right at medium local speeds my tahoe steering "slips" to the right nasty. It then seems fine. My mechanic replaced the steering box but that doesn't seem to have helped, I think he doesn't know how to solve the problem.

Gotta define "slips" to us out here in forum land, loss of control looseness, or vehicle changes direction other than where it is aimed?

I get an "oh crap" second where it feels like the wheel is going to turn all the way to the right. Then, it comes back to normal. It is only for a second and the wheel turned just a fraction. My mechanic likened it to slipping on a screw with a tread missing, it slips because a tread is gone and then catches on the next one. He replaced the steering box which I found from another tahoe. The steering overall improved but my "slip" is still there. I thought I read somewhere about a sensor in the tahoe that had to be replaced to fix this but can't find anything else on it.

I found this on another site...it describes what happens...any ideas?
Question: 1999 GMC 1500 pickup, mileage: 58,000. Has anyone been asking questions about steering problems on these trucks? My steering wheel suddenly "frees up" and turns easier when I go around a right turn. It almost feels like the steering wheel is being jerked out of your hand. I called 3 different GMC dealers and got 3 different answers. I was told it could be the power steering pump, the power steering gearbox, or the sensor on the steering column. I was told by 2 of the dealers that there is a problem, but it has not been recalled.
Answer: Scan your car for trouble codes it sounds like you have a steering wheel position sensor that has failed. Replace with new to repair problem as needed. Clear code to recheck system.

I found this on another site...it describes what happens...any ideas?
Question: 1999 GMC 1500 pickup, mileage: 58,000. Has anyone been asking questions about steering problems on these trucks? My steering wheel suddenly "frees up" and turns easier when I go around a right turn. It almost feels like the steering wheel is being jerked out of your hand. I called 3 different GMC dealers and got 3 different answers. I was told it could be the power steering pump, the power steering gearbox, or the sensor on the steering column. I was told by 2 of the dealers that there is a problem, but it has not been recalled.
Answer: Scan your car for trouble codes it sounds like you have a steering wheel position sensor that has failed. Replace with new to repair problem as needed. Clear code to recheck system.

I found this on another site...it describes what happens...any ideas?
Question: 1999 GMC 1500 pickup, mileage: 58,000. Has anyone been asking questions about steering problems on these trucks? My steering wheel suddenly "frees up" and turns easier when I go around a right turn. It almost feels like the steering wheel is being jerked out of your hand. I called 3 different GMC dealers and got 3 different answers. I was told it could be the power steering pump, the power steering gearbox, or the sensor on the steering column. I was told by 2 of the dealers that there is a problem, but it has not been recalled.
Answer: Scan your car for trouble codes it sounds like you have a steering wheel position sensor that has failed. Replace with new to repair problem as needed. Clear code to recheck system.

I found this on another site...any thoughts?

Question: 1999 GMC 1500 pickup, mileage: 58,000. Has anyone been asking questions about steering problems on these trucks? My steering wheel suddenly "frees up" and turns easier when I go around a right turn. It almost feels like the steering wheel is being jerked out of your hand. I called 3 different GMC dealers and got 3 different answers. I was told it could be the power steering pump, the power steering gearbox, or the sensor on the steering column. I was told by 2 of the dealers that there is a problem, but it has not been recalled.
Answer: Scan your car for trouble codes it sounds like you have a steering wheel position sensor that has failed. Replace with new to repair problem as needed. Clear code to recheck system.

I found this on another site...any thoughts?

Question: 1999 GMC 1500 pickup, mileage: 58,000. Has anyone been asking questions about steering problems on these trucks? My steering wheel suddenly "frees up" and turns easier when I go around a right turn. It almost feels like the steering wheel is being jerked out of your hand. I called 3 different GMC dealers and got 3 different answers. I was told it could be the power steering pump, the power steering gearbox, or the sensor on the steering column. I was told by 2 of the dealers that there is a problem, but it has not been recalled.
Answer: Scan your car for trouble codes it sounds like you have a steering wheel position sensor that has failed. Replace with new to repair problem as needed. Clear code to recheck system.

I'm having that same exact problem. Anyone know anything?

What's the correct name for the EVO? What's the part number? Does anyone other than the dealer carry it?