Toronto appeared headed for what would have been only its third win of the season, but the conference-leading Impact produced goals in the 69th and 70th minute to pull out the tie.
Montreal (9-4-3) moved two points in front of New York for the lead in the Eastern Conference. Toronto (2-8-7) remained in next-to-last place.
Andres Romero put Montreal in front with a goal in the game's opening minute, but Toronto came back with first-half goals from Jeremy Brockle, Steven Caldwell and Darren O'Dea.
Toronto outshot Montreal 17-12.