99 civic misfire on cylinders 2 and 4 CEL Blinking?

It could be anything honestly. My opinion on this: It sounds like you may need to replace your Cylinder Head Gasket. Its possible from the oil burning your gasket is shot. If not replaced eventually you could leak antifreeze into your cylinders. The though crossed my mind that if you put the spark plug cables back in the wrong order that will definitely make your car sound like a WRX STI. Your problem has to be one of these. Im willing to bet its the Gasket. You Have an Si so I would go with copper. They are usually the best way to go on a performance engine. Hope it works out for you.