Andre Miller added 25 points and 12 assists for the 76ers, who shot 57 percent after losing by 22 at Golden State on Friday night. Willie Green scored 17, including three crucial free throws in the final 18.2 seconds.
The 76ers are 11-1 in the second game of their last 12 back-to-back situations.
"I think we're a really good team after losing a game," Iguodala said. "Whenever we lose a game, we come back with a vengeance."
The Suns lost consecutive home games for the first time this season to fall to 2-4 since O'Neal joined the lineup.
"It's probably an understatement if I say we're struggling," Suns coach Mike D'Antoni said.
The Suns have fallen into a tie for fifth with Dallas in the Western Conference, but D'Antoni declined to connect those struggles with O'Neal's arrival.
"This has nothing to do with Shaq," D'Antoni said. "This has something to do with urgency and playing with heart."
O'Neal said the problems are on defense.
"We have to have some urgency and stop some people," he said. "I'm fitting in. I'm swinging the ball to the top and I'm only taking four or five shots a game. I'm just rebounding and trying to fit in. But right now we just have to stop people."
"You don't want to push the panic button and get yourself all messed up," Nash said. "But at the same time we realize how tight it is and we can't play like this for too long and put ourselves out of the playoff picture."
The 76ers led most of the night in snapping a five-game losing streak in Phoenix. Their last victory on the Suns' court came on Jan. 2, 2002.
Iguodala, a collegiate standout at Arizona, made a 50-footer from beyond halfcourt at the third-quarter buzzer to put the 76ers ahead for good 83-81. That started a 15-2 run that put Philadelphia up 95-83 with 7:21 to play on a 19-footer by Louis Williams.
The lead reached 103-87 on Iguodala's 18-footer with 4:52 to play.
Nash scored nine points on three free throws and a pair of 3-pointers, the last with 18.2 seconds left, to cut it to 115-112. But Raja Bell was called for a foul before Philadelphia got the ball inbounds. Green made the free throw and the 76ers kept possession by rule.
Grant Hill stole Miller's inbounds pass and Stoudemire's tip-in cut it to 116-114 with 10 seconds left. But Green made two more free throws, then Bell threw the ball away, the Suns' 18th turnover. Miller's two free throws at 6.3 seconds finally sealed it.
The Suns shot 27 percent in the first quarter and trailed by as many as 12 early before their 36-point second quarter, led by Boris Diaw's 13, left the game tied at 54 at the half.
The 76ers used a 9-0 spurt to take a 74-64 lead on Iguodala's 3-pointer with 4:53 to go in the third, but Phoenix responded with 15-2 run to go up 79-76 with 1:01 to go in the period.
Philadelphia coach Maurice Cheeks said it all starts with Iguodala and Miller.
"We need those two guys to play the way they played tonight in order for us to have a chance to win," he said.
- Diaw had more points at halftime (15) than he did in 50 of his previous 58 games this season.
- The Suns last lost consecutive home games since February 2007, when they dropped three straight.
- Phoenix is 22-4 against Eastern Conference teams but has dropped its last two, both at home.