Hello guys. I've got a 2000 Outback that the check engine light came on the other day. I took it to a local parts store and had him run the code and it showed a misfire in cylinder 3. I bought a set of plugs hoping this would resolve the issue. After pulling the boot off # 3 cylinder, I noticed oil on the outside of the boot and laying on the tube seal. I guess I need new valve cover gaskets and tube seals that I understand come in a kit. How hard are these to replace and what kind of time involvement is usually expected? Also, if I have a local mechanic do this, what would one expect to pay? Thanks.