What causes rough idling on a 2001 Chevy Metro after the timing belt was changed?

Rough idling on a 2001 Chevy Metro after a timing belt change could be caused by improper timing adjustments, leading to a misalignment of the engine's timing. Additionally, issues such as vacuum leaks, faulty spark plugs, or incorrect fuel mixture can contribute to rough idling. It's also possible that sensors like the mass airflow sensor or throttle position sensor were disturbed during the repair, affecting engine performance. Checking these components and ensuring proper installation can help resolve the issue.