Pampling carded nine birdies against two bogeys and now sits at 14-under 130 through 36 holes.
He moved four spots up the leaderboard to join Ernie Els of South Africa in first place.
Els posted a four-under 68 on Saturday after coming into the second round with a two-shot lead at the Principal Charity Classic in Des Moines.
"I hit a little bit better today, so that was happy, made me happier," Pampling said.
"Making good putts, making the putts we're supposed to and just not doing too many silly things, which has unfortunately been around a little bit too much the last month."
With just one stroke separating him and Els from Germany's Bernhard Langer and Canadian Stephen Ames, Pampling is planning to take the same game plan into the final round at Wakonda Club.
"If the pin allows (you) to be aggressive, you be aggressive. If not, play for the middle of the green and see if you can roll a few putts in," Pampling said.
"The greens are rolling beautiful for I don't know how many months they are, but they're rolling nicely out there. And I'm seeing them well, which obviously helps.
"Yeah, no change of strategy, just if it's there, go for it."
Langer had Saturday's low round with a nine-under 63, a performance that was highlighted by an eagle at the par-5 eighth.
David Duval (65 on Saturday), Kevin Sutherland (66) and Vijay Singh of Fiji (68) are tied for fifth, two shots back.
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