Have the tires Balanced. Then check alignment. If still shakes is it when your press the brakes? If so check the rotors and abs system. Or if it could also be the over drive if it is when shifting gears. Try running it with the over drive off.
engine rubber mounts or timin out
Need more info like what is the vehicle doing when it shakes, is it idling in park, driving down the road, braking, driving at highway speeds, etc.
you need new tirods
Check your motor mounts.
Its either timing or fuel intake problem.
usually steering shakes over 60 mph is due to front tires needing to be balanced unless you have something more serious going on.
you will need a front wheel alignment
You may have a ball joint going out or your wheels are unbalanced
road V.A
if it shakes while your braking your front roters could be warped or if it shakes while your driving try balancing the tires at a tire shop.
Carburator problems -- dirty gas -- water in gas
Your rotors are warped. You need new brake pads and the rotors turned at a machine shop or replaced.