Those blemishes, along with a birdie at the 17th by Chun In-gee, left world number two Ariya with a tenuous lead over her South Korean rival.
Ariya carded 67 for a 17-under-par 199 total, with Chun (66) alone in second place on 15-under.
Sunday's final round appears likely to be a two-woman race with Northern Ireland's Stephanie Meadow and South Korean Kim Sei-young five strokes off the lead in a tie for third.
New Zealand's world number one Lydia Ko fired a two-under 70 but slipped seven strokes behind Ariya in her quest to post a fourth victory in the event before reaching the age of 20.
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Ariya, 20, had squandered several golden opportunities before breaking through for her maiden LPGA success in May and followed up by winning her next two starts before adding the Women's British Open last month.
With so much recent success, she was not ready to dwell on her late stumble, instead opting to focus on the positive aspects of her round.
"After I won my first tournament, I kind of know how I play under pressure, so I know when I get really excited what I have to do," she told reporters.
"(I am) feeling good. I mean, I had two bogeys the last three holes but I still shot five-under, so it's still good."
Meanwhile, Chun, the 2015 U.S. Women's Open champion, signalled her intentions for the final round.
"I'm going to just focus on my game against the golf course and see where I am later," she said.
(Reporting by Andrew Both in Cary, North Carolina; Editing by John O'Brien)
