The SES was on and off one day ago, nothing special on the car. I\npulled it to Autozone to read the code out, it was P0304. One misfire\nwas detected.\n\nTwo years back, I had same issue and had probably three out of four EGR\nvalves replaced in a shop. And also rewire the spark to 0.04.\n\nLast time, when I did the oil change, I was recommended to replace\nValve Cover Gasket. Could this be related? I was told to perform\nflushing engine as well.\n\nAnd I think this is probably a minor issue to the car, no need for fix\nright now (till this weekend)?