See rotten egg smell at http://www.carsdirect.com/car-maintenance/car-exhaust-smell-understanding-where-the-problem-lies
2000 Buick LeSabre. After replacing starter. The car died and had to be jumped. Once the car had enough power it started but now the car runs rough it vibrates alot on idle the rpms are alot higher then they should and they fluxuate often. the service engine light is flashing and I get error codes po300 and po300 P. I replaced half of the 6 spark plugs and connectors (rest are in back of engine and hard to get to) as I though that might help but i don't notice a difference. The exaust has a weird rotten smell and I smell a sweet smell when turn the car on. Also the instrument panel mades a short grinding when the needles are moving after turning key anyway in the ignition.
And that start exactly after all this had happening.
My guess is bad fuel pump or catalytic converter but there are many things that can can multiple engine misfire. Any info you may provide would be greatly appreciated. -jadon

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