The car still runs fair but one cylinder doesn't fire and it's making a slight clattering noise.
No fire from one cylinder on 1998 Ford Escort
Your engine has an ignition coil that has four towers at the top each of which have a spark plug wire that goes out to each cylinder. If the problem is ignition related a spark plug or spark plug wire may be bad. A misfire like this may damage the ignition coil pac if left unattended. Other things that can cause an engine to be down in power in one cylinder may be a bad fuel injector or mechanical problems in the engine.