2005 Chevy Cobalt engine runs rough and check engine light

Went to start my 2005 chevy cobalt with a 2.2 engine. Which just hit 100200 miles, first engine turned over but failed to start, retried to start engine again, this time it started and was running rough and the check engine light was flashing. I manage to get the car to my local parts store and had them check for codes. It had two codes both indicated multi cyl miss fire. I replaced the plugs, boots, and coil pack and still has miss and check engine light is still flashing