Windstar Van Shaking horrible after startup

I have 58,000 miles on the 97 windstar, lately i notice what first start the car, it shakes horrible, you can even see the steering wheel jumping up and down, each time i come to a stop light it shakes really bad and the steering wheel is bouncing up and down. Not being mechanically enclined can anyone tell me what could possibly be causing that shaking?
thank you

engine vibration...may need a tune-up. A shop can run an engine diagnostic scan to verify if there is a misfire or something else.