Pacioretty gave Montreal a quick lead with a goal 2:39 into the game, then put the Habs ahead to stay at 2-1 with his 15th of the year less than 4 minutes into the middle frame.
That triggered a run of three consecutive second-period goals for the Canadiens, with Mike Blunden and David Deshamais each finding the net to ice the win and break Montreal's five-game losing streak.
Peter Budaj stopped 28-of-29 shots to earn the victory.
John Mitchell netted the Rangers' only goal and Henrik Lundqvist made 25 saves for New York, which dropped only its third game in 13 contests away from home.
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