Why does my car go off when its suppose to be runing iddle while driving

If the car is juststalling when at or near stop, the Idle Air Control Valve, IACV, is most likely at fault. It is located on the intake manifold near the thorrle body. It can be attempted to be cleand, but it has a diaphragm that can fail. So, most often it is best to replace it. If you clean it, use brake cleaner and rags and spray throguh ports but only towars the direction of the intake manifold. You will see mathich ports on the intake manifold that you shoudl spray out on the same manner even if you replace it. Be careful of the diaphragm and also check the vacuum hose, if so equipped that actuates the valve. It may be electrically actuated so check the connector for fit and corrosion in this case.
If the car is running rough in general, I am provinding you with a link to a diagnostic walk through.
Here is the link;

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Let me know if you have any questions.