1999 Lincoln Continental rack and pinion

Take the car back to where the work was done and give the mechanic a chance to check his work. Loose mounting bolts can cause this as well as incorrect "total toe" on the alignment.

It is very common on Ford products to remove the air springs because they do a very poor job of making replacement parts available for cars more than a few years old. Regular coil springs will work just as well and give the same ride quality. If you had air shock absorbers, those only aid the regular coil springs in maintaining ride height. The coil springs themselves may not be sufficient, but given the age of the car, the original coil springs are likely just fatigued and in need of replacement. Correct ride height is critical for proper handling, steering response, and braking balance, and on the front it also affects the alignment and tire wear. To know if your springs need to be replaced, visit any tire and alignment shop for ride height specifications. They will have a small book that shows where to take the measurements on your specific car model, and what they should be.