Q: When the car is in idle it vibrates and rpms move up and down when idle.

What you are describing is a category of inconsistent idle. The underlying fault may exist at higher engine speed but the effect is masked at those higher speeds. Among the potential underlying causes are vacuum leaks, EGR system malfunctions, malfunctioning oxygen sensors, dirty fuel injectors, fuel pump malfunction, faulty spark plugs, a faulty mass airflow sensor, or a faulty throttle position sensor. The root cause can be pinpointed, and the required repairs made, if you request an engine diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.