It helps a ton when you tell us symptoms and we guess at things. Maybe not guess, but diagnose.

1. I'm interested in your knock sensor situation because I'm pissed at my car but haven't given it a moment of time yet.

Insufficient flow, if you read up on this code, you'll find the PCM uses the MAP sensor to determine if there is a difference in flow/pressure in the UIM when it tells the EGR to open. If you have a leak, bad map etc ...your pcm might think it's not seeing a change in flow.

AKA.. you wasted money on that EGR.