Yesterday night I parked my car very nicely after work, just this morning when I start it to warm up I noticed the unusual idling of the car and it was firing up at the exhaust., I thought maybe it will come up right as soon as the engine starts to heat up I got in and drove to work, when I accelerates the car stutter and it's firing so bad at the back but I managed to get to work. The weather is so cold here and the car is parked on the grass where it's wet and cold. What could be the cause of the problem?