working on a 94 civic. Has idle issues. Idle is running up and down. Not sure how to check for engine codes so I have none. Car has a breather pipe and cone filter .

 

first check for vacuum leaks then clean the IACV also remove the intake check and clean the throttle body its most likely filthy from the cheap ebay cone filter thats most likely on your car if so replace it ASAP with a filter that actually filters the air like AEM.

 

I can only add to use throttle body cleaner not carb cleaner.