Gangjee, however moved up the Money list to 84th, up from 102nd. Overnight co-leader Jason Kokrak won the title with a four-under 67 to go to 18-under and pick his first career title.
Starting at 14-under, Gangjee, who shared the lead Kokrak, looked fine with a birdie on the second to move to 15-under.
After his second hole birdie, Gangjee bogeyed the fifth and sixth and then double bogeyed the 11th to fall way back on a crowded leaderboard.
But he can still take back positives in that he had three great rounds, including a third round seven-under 64.
Rookie Kokrak got into the field only on Tuesday, but the big-hitting player had a great week winning USD 130,500 at Hillcrest Country Club and it could well send him to the PGA Tour next year. He played the last 59 holes with just one bogey.
The next event on Nationwide is the Soboba Golf Classic in San Jacinto.