I've always found that sprints are the best way to increase turnover speed in longer runs. Try doing one long sprint day 2-4 x 400-800m and one short day 6-12 x 50-200m. Try to make the times of the shorter distances (1/2, 1/4 miles) equal to the time you need to run them for a 9 minute mile. That comes out to a 4:30 1/2 mile, a 2:15 1/4 mile, and a roughly 1:07 200m. Also, if you're running the trial with your gear, you have to train with and get used to the additional weight. It's hard to focus on your time when you're uncomfortable/unfamiliar with your gear. Best of luck to you and I hope this helps!