If your looking for the old vacuum egr valve you'll never find it.<br>It's eletric and is located to the passenger side of the thermostat housing. Held in by two bolts and has an electrical connector on top.
I dont have a pic of the exact location but I have cleaned mine out many time (95 s10 blazer vin W) So mabe I can help. Here is the exact part http://www.1aauto.com/1A/EGRValve/Chevr ... 002-522782 Take off your air intake the whole setup, it will be located just under the air intake in a horizontal position. Its a pain to get off but it beats paying someone else to do it. Here is autozones discription http://www.autozone.com/Action,locsSele ... Select.htm
Hope this helps a bit. Also I use carb cleaner to clean it out.