Is it bad when the car is having a hard time idling on its own without stalling (while warming up). this usually happens when its not that cold, (-20 to 0C, or 10F to 32F). When I start it up, it would idle high (about 2500 RPM) but a few minutes later when it slows down it will idle roughly and kill itself. Half of the time when I start it up from cold, it can warm up on its own but another half of the time I would have to hit gas once in a while to keep it going before it can idle smoothly on its own. What is causing this? (2.5L 4cyl)

most cold running issues are from the 2 temp sensors - one in the air filter can, the other on the front of the motor on the intake manifold - MAT & CTS i think are the names, or Manifold Abosolute Temprature & Coolant Temprature Sensor.