Replace/Clean Digital EGR

I can't seem to get any help from anyone I know on this subject. I have a 92 Firebird 3.1L. It has failed emissions 3 times, (main fail is NOx),I have replaced ALL emmisions sensors except EGR.
Problem is, the manual I have (haynes) doesn't cover 3.1L digital egr's.

Can someone please tell me the steps to change or clean it?

I need to go through emissions check before Oct. 21, 05. Can't afford to go to a shop and pay them all that labor $, if I can do it myself!

I want to get a better manual also, should I get a Chilton's or go with a Factory Service Manual? Thanks in advance!

The factory service manual is very pricey, but very worth it.

Not sure about the EGR. I removed mine. Maybe try google and see what you get?

Thanks for the info! I found a Chiltons for a decent price, think I will get it.