Wobble

06 G6 GT with 184,000 miles has been a great car. I just
had struts and shocks put on, brakes are fairly new. On
occasion my car will start to shake, enough i think I have a
flat tire. Its usually after coming to a stop. Accelerating
then the wobble starts, sometimes i slow down almost
stop, start really slow and gain speed slowly it will stop. But
sometimes i have to drive a bout 20 miles an hour still
shaking. The steering wheel shakes, seems like the whole
carshaakes, the faster i go the worse it gets.  I will rotate
and balance tires to see if that will help. Any other
sugesstion??