Quote Originally Posted by workmeistr View Post
Good info., Kilna. I'm only on my first replacement and will probably throw one more valve at it before looking elsewhere. I have never cleaned my tube. I got the trombone cleaning brush but will see if I clean it this time around depending on the deposits on the valve. I'm reluctant to pop off the throttle body as I'm afraid I will introduce a new air leak. Is there a throttle body seal I should have on hand just in case?

WormGod, here's what I see on Rock Auto now; are you referring to the Delphi as the "GM"?
Generally speaking, Delphi=GM

There is a gasket, mine was in good shape when I cleaned the EGR from the inside, but you may want to pick one up, they're not expensive:

http://www.amazon.com/Fel-Pro-61034-...dp/B000C2G81G/

You'll probably want to check out this thread for info on how to get the throttle body off:

http://www.vehicross.info/showthread...Cleaning-Video

Also, make sure to check the suck/blow on the EGR valve input and output, both before and after cleaning (that way you'll know if you likely fixed the problem). The big hole in the back should have strong exhaust coming out of it, and the small one should have decent suction. I think the most common cause of EGR codes is the smaller tube coming from the EGR valve to the intake, which is far more difficult to clean. It's basically impossible to clean it out right unless you open the throttle body and come at it from the front too, since it has a hard right-angle in the tube only a few inches down. You have to come at it from both sides, even with the trombone brush... it doesn't seem to be able to go around the curve.