Overnight leader Chris Smith only managed a 1-over 71 on Friday, but is tied for second place with Tom Pernice, Jr. (68) and last week's Colonial winner Tim Herron (65). The trio is knotted at minus-5.
Two-time winner David Toms shot a 3-under 67 and is tied for fifth place with tour rookie Camilo Villegas (66) and Brian Gay (67). That trio finished 36 holes at 4-under-par 136.
Stiles opened on the back nine Friday and collected his first birdie at the 10th. He missed the fairway with his drive, but hit an 8-iron to 12 feet and converted the putt.
At the par-3 11th, Stiles hit a 9-iron to 15 feet and made that putt. That was a welcome change from Thursday when he posted a double-bogey 5.
'That was a sigh of relief I was on the green,' admitted Stiles.
He made it three in a row at the 12th when his 25-footer found the bottom of the cup. Stiles parred 13 and 14, but hit a 9-iron to three feet to set up birdie at 15. He two-putted from the front of the green for a birdie at the par-5 16th.
After the turn, Stiles hit a 6-iron 18 feet past the hole. He ran home that birdie try, but trouble loomed for Stiles.
At the par-4 fifth, Stiles hit a strong drive, but found tree problems with his second. He tried to get over the trees, but hit one and the ball dropped to the ground. Stiles punched a 3-iron under the trees into a front bunker. He blasted out to 20 feet and two-putted for a double-bogey to fall back to minus-5.
He rebounded at the sixth when his sand-wedge second stopped 15 feet from the flag. Stiles rolled in that birdie putt, then built his two-shot lead thanks to another 15-foot birdie putt at the ninth.
'Just another solid ball-striking day,' said Stiles. 'You've got to work the ball around the golf course a little bit. That's the style I like to see. I'd rather there be some shot making.'
Stiles is winless on the PGA TOUR and his best finish this season in five starts was a tie for 41st in New Orleans. He owns four Nationwide Tour victories, including a playoff win this year at the Rheem Classic.
His best play this year has been in the last month, all events that featured windy conditions.
'I don't know if it's the fact that I'm used to it since I've been playing in it basically the last month or I learned how to play in it. I think I have,' said Stiles. 'I did not used to like to play in a lot of wind, but I think I've mentally gotten a lot smarter to play the right shot.'
Smith played the back nine first and traded two birdies and two bogeys. He was at 6 under par until his 6-iron approach at the fifth ran off the green. Smith chipped to 6 feet, but missed that putt to fall back into a tie for second.
Pernice had an up-and-down round with four birdies in a six-hole span from the 12th, his third hole of the round. He double-bogeyed the 18th, then had another inconsistent second nine.
He bogeyed the second, but chipped in from in front of the green for an eagle at the third. Pernice bogeyed four and five, but a birdie at the eighth got him to minus-5.
Herron flew out of the gate with three straight birdies, but mixed two birdies and two bogeys around the turn. He got up-and-down from a bunker for a birdie at the par-5 16th, then holed a 40-footer for birdie at 17.
Herron admits the relief of finally winning again helped this week.
'It was like a relief getting over a hump of a seven-year drought of no winning and being up there quite a bit,' said Herron. 'I know I've been playing well, and I don't see why I can't keep it going this week.'
Robert Garrigus, Ryan Palmer and Dan Forsman all posted 2-under-par 68s on Friday and are tied for eighth place at minus-3.
Defending champion Justin Leonard shot a one-under 69 on Friday and is part of a group tied for 29th place at plus-1.
The 36-hole cut came at 4-over-par 144 with 74 players advancing to the weekend.