2001 Pontiac Grand Prix vibration while turning

My 2001 Pontiac Grand Prix 3.8 L V6 with120,000 miles shakes/vibrates when I accelerate while turning/veering right (as when coming out of an exit to merge into oncoming traffic). It does not vibrate when I turn left. I have new balanced tires, replaced both front tie-rod ends, and the rack and pinion by a certified GMC mechanic. What could be the problem?

Have a mechanic check the CV joints, both inner & outer.
I believe that your problem is probably a failing inner CV joint, but the outer ones should be checked also.