Isenhour earlier this year won the season-opening Panama Championship. He has already earned $218,221, which should be good enough to keep him in the top-20 through the end of the year and earn a trip back to the PGA Tour in 2007.
'I saw some light at the end of the tunnel, but I didn't think it would come like this,' said Isenhour, who earned $108,000 for the win. 'Its amazing for it all to come this quickly. I'm in shock and awe. It's nice to have enough money at this point that I can play very aggressively from here on out and try to win another one.'
Paul Sheehan carded a 71 on Sunday to take second place at minus-6. Overnight leader Jeff Quinney faltered to a 3-over 75, which left him alone in third place at 4-under-par 284.
Craig Bowden, Johnson Wagner and Jim McGovern were one stroke further back at minus-3.
Isenhour, who now owns four Nationwide Tour wins, parred the first three holes before making his run. He dropped in back-to-back birdies from the fourth to get to 7 under.
The 37-year-old dropped in his third birdie on the par-5 eighth and got to 9 under for the first time with a birdie on the par-3 11th.
Isenhour gave one stroke back to par with a bogey on the par-4 13th. He moved to 10 under with birdies on the 15th and 17th. Isenhour hung on for the win despite a bogey at the last.
'You wouldn't want to have to par 18 to win the tournament,' Isenhour said. 'It was a great day because we dueled it out all day. Fortunately, I was able to hit a couple of good shots there at the end.'
Quinney, who held the overnight lead bogeyed the first, but got that stroke back with a birdie on No. 5. He fell to 6 under with a bogey on eight and fell two more strokes down the leaderboard with bogeys on 13 and 18.
Sheehan ran off six consecutive birdies during his third round. That helped him climb back to minus-5 overall. He opened Sunday with five birdies in his first six holes to jump to 10 under.
He gave two strokes back to par with bogeys on seven and nine. Sheehan got those two strokes back with birdies on 10 and 12. However, he played the last four holes in 4-over par with a double bogey and two bogeys.
Jason Dufner fired the low round of the day with a 7-under 65 to end at 2-under-par 286. He was joined there by Ryan Armour, who closed with a 70.
Christopher Baryla, Ken Duke and Matthew Jones were the final players in red figures at minus-1.