Need Some Help - 2001 Diamante - P0431, P0401, P0403

I have a 2001 Diamante LS and the check engine light came on recently. I stopped by the local auto parts place and had the codes pulled and they are:

P0431 - Warm Up Catalyst Efficiency Below Threshold (Bank 2)

P0401 -Insufficient EGR Flow

P0403 - ?

I've read this might not be the Catalytic Converter at all, and it may be either the EGR Valve or the DPFE Sesnor.

Does this make sense? What are some of the things I can check on?

Thanks

ken

I had same codes occurring then things happened in this order:

1. transmission died
2. had trans rebuilt
3. codes still occurring
4. trans acting up
5. replaced neutral safety switch and engine speed turbine
6. runs fine
7. Codes gone

Might just be gremlins but all is well now. Good luck.