Left turns make steering wheel vibrate a little

[SteveBoston]

My 99 Dodge Avenger has had some extensive work done on it lately - especially with the front suspension - R&L Lower Control Arms & Upper L Control Arm. I also had the wheel alignment done after this work & balancing of all 4 tires. My car never use to do this until after these repairs were made. So I brought it back to the Mechanic and they supposedly fixed the problem. But, obviously it started again not long after the fact. What could be causing this problem? Any help would greatly be appreciated!