Q: Egr valve insufficient flow

Insufficient EGR flow is probably not the cause of the rough or low idle and thus is just a coincidental fault. You should repair it and perhaps first, just to be absolutely sure, but rough idle is more likely due to a fuel, ignition system or air induction fault. Common causes of engine stalling and rough idle include a faulty mass airflow sensor, faulty engine coolant temperature switch/sensor (typically at cold start only), worn spark plugs, wires or defective ignition coil(s), inadequate fuel delivery or pressure (clogged fuel filter, injectors), contaminated or old gasoline, defective throttle position sensor, faulty idle air control valve, leaks in the EGR system, intake vacuum leaks, and so forth. If you request an engine stalling/rough idle diagnostic the responding certified mechanic will get this resolved for you promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.