Idle Rpm Fluctuates: Civic

Check Idle Air Control Valve (IAC). See appropriate Diagnostic Trouble Code (DTC) in SELF-DIAGNOSTICS - CIVIC article.
Check idle speed adjustment. See ON-VEHICLE ADJUSTMENTS article.
Inspect/adjust throttle cable. See ON-VEHICLE ADJUSTMENTS article.
Inspect throttle body for sticking and binding.
Check for worn throttle body.