Hi all, This morning, I had problems starting my car. It's been pretty cold lately. The car turned over then I tried to start but would not stay on idle. It would stall. I tried to start several times but was starting rough. The Tach would surge roughly then the car would shut off. Finally started it again after several tries and kept the gas pedal on. It was rough for about 30 seconds and it finally settled down and smoothed out. The car ran fine when it warmed up. Anyone have an idea on what caused this roughness. Am I right to assume that maybe I need to change my O2 sensor?