I have a 90' 240 Wagon and recently it was in the shop for a warn drive shaft support bearing (darn humming), anyway the humming is gone now; however I have noticed something new. When I go to accelerate from either a dead stop or very slow roll the car shakes somewhere between 5 and 20 miles an hour, I can't get an exact speed as the intensity of the shake varies with how hard I’m accelerating. It only happens when I give it gas, and if I baby it up to speed the shake is almost gone. One person told me to bring it back into the shop because it sounded like they had improperly aligned the drive shaft, but any help would be appreciated.

Thanks