Park, who is a rookie on the PGA Tour, did not register a bogey for the second consecutive round as he made two birdies apiece on his front and back nine to finish with a third-round 66.
His highlight of the round came on the par-three eighth when his tee shot from 199 yards fell just 11 inches away from the hole, allowing him to tap it in for an easy birdie.
Bohn excelled during the third round as he recorded a career and tournament low 61. Bohn bested Scott Langley's 62 in the first round as he made five birdies on his front nine and another on the 10th to kick off his back nine.
However, Bohn's only error of the round came on the very next hole as he missed a 14-foot par putt to register a bogey.
But, things returned back to normal after that as Bohn made consecutive birdies on the 14th and 15th before finishing his round on a high with a duo of birdies on the 17th and 18th.
O'Hair may not have had the most glamorous start to his third round as he made two birdies and two bogeys on the front nine, but he shot up from tied 10th on the leaderboard at the beginning of the day to tied first due to his back nine, which consisted of four birdies.
In addition to sitting atop the leaderboard, O'Hair also had one of the putts of the day as he sunk an incredible 40-foot birdie putt on the par-three third.
Molder began the day just one stroke off the lead and gained some early momentum with three birdies on his front nine. But, he was unable to carry his momentum into his back nine as he made nine successive pars to finish off his round.
Sitting one stroke behind Park, Bohn, O'Hair and Molder are Justin Thomas, David Hearn, Danny Lee and Chad Collins.
World number three Bubba Watson moved up the leaderboard to tie in 17th place despite his turbulent third-round 68, which saw moments of brilliance like his 31-foot birdie putt on the par-five fourth and moments of madness like his two-foot par putt blunder on the par-four first.
Meanwhile, former world number one Tiger Woods slipped down to 47th place after carding a disappointing third-round 71, which consisted of four birdies, three bogeys and a double bogey on the par-four 11th.