Jason Terry led Dallas with 19 points, Dirk Nowitzki had 17 and Shawn Marion added 15. Nowitzki played in his 884th game to surpass Brad Davis as Dallas' career leader.
Dallas led by eight early in the fourth before the Suns' reserves started the rally.
Earl Clark hit his first career 3-pointer to pull Phoenix to 92-90 with 9:41 left. Dallas made it 98-93 on Jose Barea's driving layup with 7:25 to go, but didn't hit another shot from the field until Shawn Marion's short jumper with 3:31 left.
Amundson gave Phoenix its third lead, 99-98, on a driving dunk with 5:25 remaining, Jared Dudley hit two free throws, and Amundson added a free throw to put Phoenix ahead 102-98 with 4:33 left. Marion's jumper pulled Dallas within two, but Nash hit a 3-pointer, and Amundson scored on a scoop shot with 1:46 to go to make it 107-102.
Dragic finished with 13 points, Amundson had 12, and Dudley eight.
NOTES: Dallas lost for the fourth time in 21 games when scoring more than 100 points. ... Stoudemire, who broke the 20-point mark for the first time in four games, did not have a defensive rebound in 27 minutes of action. ... Phoenix is 11-2 at home against the Western Conference. ... The Mavericks trailed for two possessions and 40 seconds over the first three quarters. ... Marion was making his third trip back to Phoenix with his third team since he was traded by the Suns to Miami midway through the 2007-08 season in the Shaquille O'Neal deal.