The defending NBA champion Spurs never trailed in winning their ninth consecutive playoff game and 13th of 14, dating to last season. They can complete the sweep on Sunday in Phoenix. No NBA team has come back from 0-3 to win a series.
It's the first three-game losing streak for the Suns this season.
Phoenix acquired Shaquille O'Neal to better match up with the Spurs, but the Suns are one loss away from being swept in a seven-game series for the first time since the Los Angeles Lakers did it in the 1988-89 Western Conference finals.
Tim Duncan added 23 points and 10 rebounds and Manu Ginobili scored 20 points in the Spurs' fourth consecutive playoff road victory and ninth in their last 11.
But Parker did the most damage, often on a pick-and-roll that has flustered Phoenix all series. With three different defenders trying to stop him, he made 17-of-26 shots.
The Suns cut the lead to 13 points twice in the fourth quarter, the last on Raja Bell's 3-pointer with 7:35 to play, but Parker countered with his first 3 of the game and the Suns were finished.
The packed house in the Suns' first home game of the playoffs booed San Antonio coach Gregg Popovich's "Hack-a-Shaq" tactics in the first half, but they turned on the home team when the Spurs took a 23-point lead on Ginobili's 3-pointer with 5 1/2 minutes left in the third quarter.
Amare Stoudemire had 28 points and 11 rebounds to lead Phoenix, which was last swept in a series when Portland did it in a best-of-five matchup in 1998-99. Leandro Barbosa scored 20 points and O'Neal, who finished 9-for-17 from the free throw line, had 19. Steve Nash had seven points on 3-of-8 shooting with nine assists.
Phoenix took big early leads in the first two games in San Antonio. The Spurs were in control of this one from the start.
San Antonio made 10 of its first 13 shots, including five of six jumpers by Parker. A 17-4 outburst capped by Parker's 22-footer put the Spurs up 27-12.