It's a good performance. It's not as "mind-boggling" as people remember it.
Nobody ever mentions the two bad snaps on Houston's last two punts and everyone just ignores Montana's fumble with two minutes left. And the winning touchdown was 90% Haines.
The "chicken soup" part of it is also largely overstated. After coming back into the game, Montana went 1/12 with two interceptions (and nearly a third) before the punt block returned for a touchdown. A different punt block also gave him the ball at the 11, and he went 0-3.