[olopezm]

Plugs and wires is a good place to start. You mention the silver tip on the coil is corroded, that can cause the misfire too. Use a brass brush and give it a good clean, if the wires haven't been changed for a long time replace them too...

If the belt is chewed replace it too, it may be getting weak and a broken belt is something you don't want as it can happen while coasting and you might not notice it since you don't look at the instrument cluster all the time when you're driving...

Oscar.