You probably have oil in the spark plugs. Is the spark plug covered with "dark" fluid?
Usually if there is a leak in the valve cover gasket, oil can leak into the plugs.
Are there any trouble codes?
Here is an article you might find helpful:
I have attached spark plug replacement as well and valve cover gasket replacement.
Let me know if you have any questions.
Images (Click to enlarge)
Wednesday, July 14th, 2021 AT 1:01 PM