Sloppy Steering After Lift?

Hi guys n gals, well im going to jump right into this so, i just purchased my first ever vehicle which is a 96 Tahoe 2dr 4x4 with 52k original miles, 4" lift, 33" tires, mild build 355 engine, upgraded transfer case, towing shift kit in the transmission and 410 gears. (All upgrades done by previous owner)

The lift is only is a year old and less than 1000 miles put on since installed. The complete kit was ordered specific to this vehicle then professionally installed by a 4x4 specific shop in South East Iowa.

The problem is with sloppy or wondering steering. It actually feels like its drifting back and fourth while driving, quite scary at times. Every single part under this Tahoe is brand new from nuts to springs. He also had it aligned twice in that short 1000 mile time frame and it still wounders and that is actually why he sold it to me so cheap, just tired of dealing with it.

He was stumped because he had that exact same kit installed on his 98 Tahoe and a 94 Suburban with no steering issues. Any thoughts or suggestions will be greatly appreciated. Thanks!

Super late response, but that sounds like the variable power assist. I bought my 99 2 door new, and it did that - especially in the winter (?) and on slow sweeping turns, like freeway entrance ramps. Feels like it lets go then over-assists. Definitely unnerving when it happens. Mine went away for years, but I just did a lift and new larger tires and it seems to be back with a vengeance. I have more R&D to do, but I've read that it is likely the steering wheel position sensor or steering speed sensor? Could be part of GM Bulletin #07-02-32-001