Timing belt. misfiring engine
What causes a car to idle good and run rough when you give it gas?
god i do
That is about your average idle RPM. It depends on what car you have and the age of your car. If it bothers you, i'd recommend going to a place that fixes cars.
change your fuel filter, it could be plugged.
Fast idle motor is not working. This is allowing the idle to fall below the threshold of what it should be when the A/C is on.
Because the engine is running. Shut it off or give it gas and it will not idle.
When the ac is running the idle should be raised to compensate for the extra load. If the idle isn't rising then the car will cut off.
If the car is starving for fuel or air (low power at idle), the car will stall while turning.
Fuel injection or fuel contaminated?
Cylinder misfire. Possibly failed or failing engine mounts.
A vacuum leak (Brake booster).
A sloppy, worn out of adjustment timing belt.