Q: White smoke coming out of exhaust

White smoke is an indicator that the engine is burning coolant. The fact that the engine idles poorly points toward a problem with the cylinder head; most commonly, the head gaskets. When the gaskets fail, a leak between the cylinder(s), and the cooling system is common. On the intake stroke, the pressure in the cylinder is less than the cooling system. Coolant will enter. On the power stroke, compression is lost to the cooling system, resulting in a loss of power. In any case, the cooling system will need to be inspected. I would not drive the car like this, as you can damage the engine further. YourMechanic can send a top-rated technician to your home or office to diagnose and repair your white smoke concern.