John Mallinger carded a 65 to move into third place at 12-under-par 201. He was joined there by Fran Quinn (64). Steve LeBrun took fifth place at minus-11 thanks to a third-round 66.
Second-round leader Kevin Durkin struggled to a 5-over 76. He tumbled into a tie for 28th at 6-under-par 207 on the North Course at Crestview Country Club.
Couch, who won the Rheem Classic and LaSalle Bank Open earlier this year, knocked his second shot to a foot at the first and kicked that in for birdie. After a bogey on two, the five-time winner on the Nationwide Tour sank another short birdie putt on three to get to 9 under.
The 32-year-old made it two in a row as he drained a 15-foot birdie putt on the fourth. Couch tripped to a bogey at the next. He got that stroke back with a birdie on seven from 7 feet out.
Couch drained a 15-foot birdie putt on the 10th to move to minus-11. He dropped a wedge within 2 feet to set up birdie on the 13th. He got to 13 under when he drained a 10-footer for birdie at the last.
'I was hoping to get up near the lead and I was able to do that,' Couch said. 'My goal was to shoot 4 under so I did one better than that.'
If Couch goes on to win, he would gain the automatic 'Battlefield' promotion to the PGA Tour. The last player to earn that promotion was Tom Carter in 2003.
'One of my goals is to get the 'Battlefield' promotion,' said Couch. 'So it is on my mind, but I'm trying not to dwell on it. This is definitely the closest I've been since I got my second win.'
Hoffman opened with a bogey on the first. He two-putted for birdie at the next to recover that lost stroke. The 28-year-old sank a 4-foot birdie putt on the fourth to move to minus-10.
The 2004 Permian Basin Charity Golf Classic winner rolled in another 4-footer for birdie on No. 9. Around the turn, Hoffman kicked in a 2-footer for birdie at 11.
Hoffman faltered to a bogey on the 12th, but came back to birdie 14 to get to 12 under. Hoffman joined Couch in the lead as he holed a bunker shot for birdie at the 16th.
'I'm trying to keep Couch on this tour,' Hoffman joked. 'I played pretty good. I hit the ball pretty good today. I was a little disappointed with the three-putt par on 18.'
Joe Daley fired a 6-under 65 to move to 10-under-par 203. He was joined in a tie for sixth place by Shane Bertsch (67), Deane Pappas (70), Jason Schultz (70) and Esteban Toledo (67).
Jeremy Anderson, Mathew Goggin, Joel Kribel and Tim Wilkinson are one stroke further back at minus-9.