Half halts, Approaching at a slower gate (instead of canter, trot), putting down trot/canter poles, Cavaletti work (if you don’t do this, google it—seriously), and sometimes making sure you warmed them up well can help. Best of luck.
Try putting canter polls about a stride before a Large or small x rail it will make your horse think a about the polls Instead of rushing! Then as you go further along move the polls back stride by stride until your horses stops rushing! And if she rushes to it move the poll closer!