Had this code, MIL flashing, replaced sparkplugs and boots and springs. Ran great for a while then MIL started flashing. Repaced #1 coil pack. Ran good for a day then started flashing intermittingly. Flashes for a few minutes then it stops fashing for a few minutes, then will start flashing again. Took iot apart again and everything looks good. Sparkplug a little black. Could the new coilpack be bad?