It was a 1-1 contest when Tanguay put a wrist shot past Jean-Sebastien Giguere with 4:43 to play in the second. Less than a minute later Calgary had a 4-1 advantage and had driven Giguere from the game.
The Flames won their second straight and prevented the Maple Leafs from putting together their first three-game winning streak since the opening week of the season.
Bourque's goal was his 13th of the campaign, one more than he had all of last year.
Miikka Kiprusoff made 17 saves to claim the victory. He gave up the first and last goals of the game.
Giguere allowed four goals on 24 shots before being replaced by Jonas Gustavsson.