Have the farrier come
Have a lookover by a vet
Get a chiropractor for her
Make sure your saddle fits really well
And she needs hours and hours of walk walk walk, getting her to relax and stride out. I find what helps me is a bit of dressage; using each corner properly, figure 8's, in a ring, make sure you can see her eyelash on the inside without just bending her neck. Backing up here and there, ground poles.
You can get a nice gait, but she needs a lot of work prior to asking for it. I know it's in there.
How old is she?