And it could be the rack itself going bad, seals will leak internaly and push it side to side slightly without you turning steering wheel. Scary when it happens isnt it? had them do this before, expecially on older Omni/K cars.
And FYI, i bought a remanu. rack from Advance Auto for my 91 i had, it lasted less than a year before puking all the PS fluid out of it, total junk. So uless you do have something binding or loose, or whatever, me..... id rather take a chance on a original junk yard rack if i couldnt afford a new and not rebuilt one. Unless someone someplace remanufactures ones better than Advance, which wouldnt be hard to do.