Does the car run rough even in gear and moving if idle air control valve is bad it runs smooth at high rpm?

A bad IAC valve will often cause a rough idle, but it's less likely to directly cause a rough running condition *while driving at higher RPMs*. At higher RPMs, the throttle body's main function takes over air intake control, minimizing the IAC's influence. Therefore, if the car runs smoothly at high RPM but rough at idle, a faulty IAC valve is a strong suspect. However, if it's rough at both idle and higher RPMs while driving, the problem is likely something else entirely, such as:

* Spark plugs or wires: Misfires are common causes of rough running across the RPM range.

* Fuel injectors: Clogged or malfunctioning injectors can lead to inconsistent fuel delivery.

* Mass airflow sensor (MAF): A bad MAF sensor provides inaccurate air flow data, causing poor fuel mixture across all RPMs.

* Engine sensors: Various other sensors (e.g., crankshaft position sensor, camshaft position sensor) can cause rough running if they're faulty.

* Vacuum leaks: Leaks in the intake system will affect air/fuel mixture negatively, creating rough running regardless of RPM.

In short: A bad IAC is a *possible* cause of rough running at idle only, improving at higher RPMs. If it's rough at higher RPMs as well, look elsewhere for the problem.