With the victory, the Flyers climbed into third place in the Metropolitan Division, pending Columbus' result in Los Angeles later in the night.
Mason fought through cramps - he thought they came from dehydration - in his left leg in the last two periods. Trainer Jim McCrossin tended to him on the ice midway through the final period, and the goalie skated to the bench during a break in the action and kept flexing the leg.
"It started in the second period and just got progressively worse," he said, adding that if the Flyers had a bigger lead, he may have asked to come out, but that he didn't want to put Ray Emery in a tough situation by coming in cold.
Mason finished the game and nearly notched his third shutout in the last five contests. Rookie Nathan MacKinnon, with his goalie pulled, got the Avs to within 2-1 by scoring on a bad-angle shot to the short side with 2 minutes, 50 seconds left.
The 6-foot-4, 217-pound Mason made his sixth straight start - equaling his longest stretch of games this season - and said he would be "good to go" at Friday's practice.
"I'm feeling comfortable. I don't want to get ahead of anything. Just taking it one game at a time," he said.
Raffl gave the Flyers a 2-0 lead when he converted Sean Couturier's pass with 12 minutes, 55 seconds left. Couturier took the puck away from defenseman Nick Holden behind the net and fed Raffl for his third goal in the last four games.
Mason is 4-1 in his last five starts with a 1.41 GAA and a .955 save percentage since he had a spirited conversation with Hall of Fame goalie Bernie Parent.
With 13:39 left in the second period, the Flyers, who went 2-1 on their difficult California trip, took a 1-0 lead when Streit's power-play blast got past Semyon Varlamov as Steve Downie set up a screen in front. Streit's shot appeared to deflect off a Colorado defender.
Streit said the Flyers made it "too complicated" when they failed on an earlier five-minute power play that was eventually trimmed to three minutes because of a penalty to Wayne Simmonds. Colorado's Patrick Bordeleau drew a five-minute checking-from-behind penalty (and a game misconduct) by sending Brayden Schenn headfirst into the boards late in the first period. Schenn was not seriously injured.
On the extended power play, "we didn't get enough shots through," Streit said. "But this time, we did. We kept it simple."
It marked the eighth straight game that the Flyers had scored a power-play goal.
Mason and Varlamov took turns making sensational saves throughout the game.
Mason, 25, said his informal meeting with Parent at the Flyers Wives Carnival was "more philosophical than anything" and not about the technical aspects of goaltending. At the time, Mason was in a six-game slump.
"What I said to him was simple," Parent said the other day. "I looked him in the eyes and said I really believe in him. I told him, 'You're a good goalie, but there are going to be rough spots. . . . I had some tough times, too.' I told him, 'Don't judge yourself based on a couple rough games. Always look at the end goal, which is to win the Cup.' "