I'm at such a loss. This might be a long read, but want to be as detailed as possible.
I had P0307 and P0303 codes. Since they were on diffent coil packs, and I assume everything was probably still original so I decided to change both coil packs (from Lucky8), plugs (Bosch Platinum), Wires (8mm Kingsborne), new valve cover gaskets and intake gasket. This got rid of the P0303 but I'm still randomly getting P0307. I say "randomly" because sometimes I can drive all day and never have a problem, then the next day it starts missing immediately. And then anything in between. There doesn't appear to be any trigger that makes it happen as I've driven it hard and easy and sometimes it happens and other times not. I had put new Bosch O2 sensors on shortly before the original problem.
With the problem coming and going, it really has me about to loose mind.
Any thoughtsm
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How does plug #7 look?

 

When this first started, that was the first think I checked and it wasn't bad. A little carbon, but not horrible. I cleaned it up and checked it about 50 miles later and was still good.