2006 Ford Focus steering

The problem sounds like a suspension problem. I would look at either the tie rod ends, or the ball joints. If either are broken or severly worn the could easily cause the shaking problem. The other thing I can think of is possibly the stabilizer links. Double check with the dealer on any possible recalls having to do with the parts. I know the early 2000, and 2001 had the front struts, coil springs and stabilizer links recalled. Hope this helps and good luck.