The loss was ACU's first of the three-day tournament (4-1) and first since Opening Day when it lost 6-3 to East Central.
ACU (12-2) jumped out to a 2-0 lead in the third behind RBI from Sarah Martinez and Megan Brigance, but the Gorillas responded with a five-run fourth, in which they wrapped three extra-base hits around a pair of fielding errors.
Amanda Castro led off the fifth with a home run, followed by three more of her teammates loading the bases via error, double and walk. Starter Peyton Mosley appeared to be out of danger after inducing a 5-2-3 double play, but then walked the No. 8 batter before giving up a go-ahead two-run double by Cheslyn Mitchell.
Pittsburg State extended its lead to 6-2 in the fifth with an unearned run vs. Shelby Hall, and tacked on two more vs. Caitlyn Crain in the sixth. Mitchell reached on error to begin the inning and two outs later scored on Kreslee Ketcham's bases-loaded double.
Brigance blasted her second home run of the year in the sixth for ACU's final run of the game.
The Wildcats begin Lone Star Conference play next Friday and Saturday with a three-game series at Incarnate Word.