A dirty throttle body can cause a rough idle, When the throttle body is dirty it chokes the engine from getting air when at idle. The throttle body is easy to clean, should be done around every 30k miles.
A bad camshaft phaser solenoid could also cause a bad idle. This solenoid controls the camshaft timming. Sometimes the solenoid will leak oil out of the connector, if this is happening you will have to replace it.
You should check the air filter to make sure its clean, the filter can be hard to inspect. Some techs will not check it during oil changes due to its hard to inspect.
The spark plugs should be replaced, if they are bad it will cause a mis-fire. If they are worn it can cause a rough idle, the coils have to get move voltage to fire a worn spark plug(excessive gap) which causes the spark plug to fire late.
A dirty fuel filter would cause a lack of power, not a rough idle but should be replaced every 30k. Also you should have the injectors cleaned at the same time.
The picture below is the camshaft position actuator solenoid.