Padraig Harrington, who held the 36-hole lead, stumbled with a closing bogey to finish six shots off the pace. The defending champion carded a third-round 70 to stand at 5-under-par 211.
Tournament host Tiger Woods struggled early with the putter, but battled through a difficult round of 72 to finish alongside Fred Couples and Chris DiMarco at 2-under-par 214.
Love, who led after the opening round, jumped out of the gate with a birdie at the par-5 second. He followed that up with a birdie at the par-3 third after his tee shot stopped eight feet from the cup and kept rolling with a birdie at the par-5 fifth to make an early charge amid improved scoring conditions at Sherwood Country Club.
The 39-year-old, who quarrelled with the wind that plagued the earlier rounds, played his tee shot to six feet at the par-3 eighth and drained the putt for a birdie.
Love, who played alongside Woods on Saturday, added a birdie at the ninth and got up and down from a bunker for a birdie at the par-4 10th.
'I knew I had to be patient today. I knew playing with Tiger two days in a row that one of us was going to get going and get a good round and I wanted it to be me,' said Love, who won four times on the PGA Tour in 2003. 'Today it was a day to hit the irons good and I got on a roll.'
At the par-5 11th, Love ran home a three-foot putt for his fourth straight birdie to take control of the tournament at 9 under.
Love converted a 10-foot putt for a birdie at the par-5 13th and dropped his tee shot inside four feet for a birdie at the par-3 15th. Love then reached 12 under with a birdie at the 16th, but three-putted for a bogey at the 17th to match the course record.
'You gotta beat the golf course and you gotta beat the guy with the lowest score,' said Love, who won this event in 2000. 'You gotta play the golf course and I'm learning that more and more.'
Like Love, Choi was on fire early and the South Korean collected birdies on each of his first three holes.
Choi moved to minus-6 with an eagle at the fifth, but he faltered with bogeys on each of the next two holes.
The 33-year-old recovered with a birdie at the par-4 ninth and stopped his approach inside five feet for a birdie at the 10th.
Choi tallied his third consecutive birdie at the 11th, but found trouble with a bogey at the very next hole. He was able to counter with birdies at the 13th and the 16th for a round of 65 and an 8-under-par 208 total.
'I think that playing in this tournament with such a strong field, to be able to have a good performance or even come out with a win will help my game tremendously going forward and will give me the confidence I need,' said Choi, with the help of a translator.
Masters champion Mike Weir finished alone in fourth place at 4-under-par 212. Justin Leonard was one shot further back at 3-under-par 213.
Woods, who won this event in 2001, picked up a birdie at the second, but struggled with a three-putt bogey at the third. He found trouble again with a bogey at the fourth and dropped another shot with a bogey at the eighth.
The top player in the game responded on the inward half with three birdies and a bogey to finish nine shots off the lead.
Robert Allenby carded an even-par 72 to finish alone in ninth place at 1-under-par 215. Vijay Singh followed at even-par 216.
PGA Championship winner Shaun Micheel joined Nick Price at 2-over-par 218.
Jay Haas joined Kenny Perry at 7-over-par 223. Darren Clarke and British Open champion Ben Curtis were one shot further back at 8-over-par 224.