I’ve been having this issue for quite some time now p0300 code. And I’ve been doing a lot of research and everything that people told me to replace has not helped. So far I have changed sparks, coils, fuel injectors, valve cover and the gasket, as well as my upper plenum. On a cold start the engine shakes pretty hard and idle is rough at times but once it gets warm engine stops shaking and idles normally. When I changed my spark plugs I noticed some had a lot of oil and were very burnt so that’s why I changed my valve cover gasket and sparks. I went on a drive with the new spark and from a complete stop if I do a pull the car will work perfectly but as soon as I let off the gas it goes back to misfiring, although this stopped once I changed my valve cover now all the time it runs bad. Does anyone have any suggestions on what else I can check or due because I’ve spent too much money on things that have not been fixing it. I also ordered a mad sensor should be coming in next week so I will check if that helps but I highly doubt it.