Computer problem
2006 Chrysler 300 6 cyl Two Wheel Drive Automatic 63000 miles

I bought my 2006 Chrysler 300 (2.7L V6) last week from a repo lot -- I got a great price but it also came with some work that needed to be done. The MIL was on so I checked the codes:
P0302 - Cylindar 2 Misfire
P0202 - Injector 2 Control Circuit High
P0406 - EGR Sensor A Circuit High
Today I replaced the spark plugs and EGR valve. I ended up ordering the EGR valve and gaskets from rockauto.com because I couldn't find Anywhere around here that had them. Unfortunately they sent the wrong gaskets, so I went up to the parts store and got some cork/rubber gasket material and made my own (and reused the old EGR gasket that goes into the plenum, though that still seems to be in pretty good shape). After I put everything back together I started it up and found that, even though it runs flawlessly now, I still had the error code:
P0406 - EGR Sensor A Circuit High
and a new one: P0403 - EGR Circuit Malfunction

Anyone have any ideas why I'd be getting these errors after installing a new EGR? Could it be the gaskets? or are there certain conditions I need to provide before it resets itself?
Like I mentioned, it seems to be running perfectly, but I need to take care of this MIL problem to pass inspection.

And while I'm at it, anyone know what this part (tinyurl.com/n2z5r6) is or where it goes? I'm thinking it might have something to do with my problem. Thanks for your help..!