Pontiac Repair: rough running 2000 pontiac bonneville, catalic converter, pontiac bonneville

Question
My 2000 pontiac bonneville started running rough about two days ago and the check engine light came on. My son used a portable diagnostic device from his work to check the engine. It indicated that there was a misfire. He replaced all 6 spark plugs and wires as well as one of the coils. The check engine light is now flashing instead of just lit and the problem is still there.
What could be a possible cause other than what has already been tried. We also checked all the fuses.

Answer
Hi Darla:

the flashing light indicates an engine misfire that is bad enough that can damage the catalic converter. First off you need to check for spark on all 6 cylunders. you either going to have just one dead cyliunder or 2 2 being because they are paired 2 per coil if it has a bad coil it will take out 2 cylinders. if it's the cyinder(S) that the coil was replaced on and there still is no spark then chnaces are it has a bad ignition module.... that is the spark end of it. it could have a bad fuel injetor too or an engine mechanical issue. A lack of spark is the more common issue with these engines. good luck :-}