rough idle on 2002 Cadillac DeVille

4.6 noth star i change the plugs and wires crank sensors fuel filter code PO300 mutiple mis fire what else could this be

Asked by for the 2002 Cadillac DeVille
Here is a ton of great information about the P0300 code:
1 more answer
Try the Vacuum Hose's or Brake Booster.