So a few days ago my car tripped 100k miles. I bought it when it had 47k miles and have never changed the plugs or ignition coils. It started having a rough idle, so I decided to change out the coils and plugs. Now the car has a misfire that is sometimes bad and causes shuttering, loss of power and a miss/dip in rpms while idling with an occasional flashing CEL (usually only when under heavier acceleration.) 4 brand new plugs and 4 brand new ignition coils and I have a worse running vehicle. Any ideas? The plugs are NGK Irridiums gapped at 0.45 I believe which they guy told me was the recommended gap and the coils are just duralast brand from autozone.