Rust gave Pittsburgh a 2-1 lead on another power play, deflecting a point shot from Pierre-Olivier Joseph at 19:47.
The Penguins are 13-for-35 (37.14 percent) and have scored at least one power-play goal in nine consecutive games, their longest streak since scoring in 12 straight from Feb. 3-26, 2013.
"We weren't as good as we would've liked to be through the first half of the game," Rust said. "We weren't on our toes. We weren't fighting that hard. For some odd reason, we weren't in a game that we should've been. I think getting those power-play goals really gave us a shot in the arm."
Crosby extended it to 3-1 at 8:40 of the third period, going forehand to backhand and through the five-hole off a pass from Jake Guentzel for his 18th goal.
Kreider took a pass from Vincent Trocheck on a 2-on-1 for a wrist shot, cutting it to 3-2 at 10:03.
"Had a lot of fight in the third," Trocheck said. "I liked the way we played for the most part, but there were a few shifts during the second, and I just feel like that goal in the third, that we need to tighten up."