1996 buick roadmaster idling rough and missing....any answers?

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I have a 1996 Buick Roadmaster 350 LT1 5.7, I am having some issues with the vehicle idling rough and seems to be missing. When I turn on the AC the car runs a little better and sometimes after shutting the AC OFF THE CAR SHUTS OFF.I went to AutoZone and had my car put on the computer and I got a EGR code P0400, Mass Air Flow code P0100, and a Catalyst code P0430. I replace the EGR, and mass air flow sensor, and my car is still doing the same thing. I was also told I may have a leaky water pump. I just recently installed new AC DELCO plugs and wires and a new air filter. Any ideas on what to try next or what could be my problem? NEW PARTS INSTALLED: PLUGS WIRES AIR FILTER EGR VALVE MASS AIR FLOW SENSOR See a video of my car running at https://www.youtube.com/watch?v=K028uIUMlpM&feature=youtu.be