How much dielectric grease and exactly where did you put it?
I wouldn't use dielectric grease except a super-light film, just barely enough to feel it on the tip of your finger, applied as a film to the inside of the opening in the coil-pack.
Dielectric means it doesn't conduct electricity.
You only want a tiny smidge to prevent the rubber part of the end of the coil-pack from sticking to the end of the plug.
You do not want it all over the plug's metal end.
Same thing with anti-sieze grease on the plug threads.. barely any at all, almost none.