Does the "center point" of the steering gear correspond with the wheels being straight ahead? If the gear is even slightly off-center when traveling straight, there's going to be slack inside the steering box. Hopefully, you installed an adjustable drag link that will allow you to establish the right sector gear preload and then adjust the wheels straight ahead. I have fixed "steering wander" problems on dozens of vehicles by simply center-pointing the steering gear.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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