Oil patch where the PCV breather hose goes into the valve cover on the driver's side.

98 GT.


Recently my car started to have a rough idle and is stuttering while driving.
Today I noticed that there is an oil patch near the PCV breather hose that is on the driver's side. Could this produce a vacuum leak and cause the car not to drive properly?
If so, do I just need to replace the hose itself or is there something else I need to replace?