Engine misfire causes

[spookybathtub]

My check engine light came on, again with a misfire on cylinder 4. These plugs have been in for 100k miles so I changed them, even though the gaps are good and they don't look burnt. I found a lot of oil in coils 1 and 2. That same slow leak from 3 years ago has gotten worse. So I'm going to replace the valve cover gasket, and hopefully that takes care of it.