Dear Forum I own a 2004 Colorado and last week the service engine light came on and it started running rough. I had a mechanic friend hook it to the OBD II tester and it showed codes 0300 and 0506. I changed all of my spark plugs and cleaned my throttle body. It contiued to run rough and the service engine light was still on with same codes present. Ive checked everything there is to check and have replaced what appeared to be a bad ignition coil. STILL RUNNING ROUGH AND SERVICE ENGINE LIGHT ON. IT NOW BLINKS WHEN I AM DRIVING. PLEASE HELP!!!!!!!!