Do you have a conventional steering box or a rack & pinion? There's a sector gear preload adjustment on a regular steering box that most alignment shops either don't know about, or choose not to do unless the customer insists on it. It can cause the wandering you're describing. PM me for details.
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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