PTBGSVT

Ok, call me lazy, but I'm trying to save some time and $ by asking someone who knows already instead of figuring it all out myself. Here are the quick details:

1998 Countour SVT, 270,000 miles. Original everything, even the clutch!
Shows codes for CAT efficiency and PO401 for EGR.
Pings loudly under full throttle over 5000RPM, and pings a little (not loudly)under medium load in very slow traffic or hot weather.

With this mileage, should I not just go ahead and replace EGR and DPFE sensor? If so, would someone please give me a brief scoop on where they are (or point me to a good info resource) and what pitfalls might make me regret trying to DIY this project? I'm an OK backyard mechanic; just don't have time to putz around with this any longer than I have to.

Thanks
Mark
The Old Dominion, USA

PTBGSVT

A week goes by and nobody answers... Nevermind. I'll just buy a shop manual.