The 36-year-old DeCorso had a 14-under 274 total on the 7,781-yard Kinderlou Forest County Club course, the longest in Nationwide Tour history.
He earned $112,500 to jump from 38th to fourth on the money list with $148,976. The top 25 at the end of the season will earn 2009 PGA Tour cards.
"I think this eclipses my career-best check by about $100,000," DeCorso said.
"Three weeks ago, I changed everything. Thanks to my new swing coach, Greg Towne, for such a quick turnaround on my game. I went into the swing change thinking long term. My goal has been to shoot all four rounds in the 60s. I achieved that goal and I'm very proud of myself for sticking to my game plan all week."
The former Kent State players finished fourth last week in the Henrico County Open.
"I don't think I had any patience last week in the final round," DeCorso said.
"You can learn from everything. Today I kept to my routine, I didn't get quick. I had no idea where I stood. I told my caddie to tell me on the 18th tee where I stood only if I needed a birdie to tie. I didn't want to know."
Molder closed with a 69, and Owen shot a 72.