Flashing check engine light, and no das...

The check engine light is flashing and the car is running rough. I've had the spark plugs, and valve cover gasket recently changed. Oil was getting onto the threads of one of the spark plugs and fouling it out. I've had the same spark plug changed twice, because the oil was still getting on the threads. Not sure where or how the oil is getting on the same plug, even after the gasket was replaced. My dashboard lights also don't work most of the time. They very rarely come on anymore. I've already checked the fuses, and their fine. What else can I check for these two problems? Any help would be appreciated. Thank you. D.