I am wanting to replace the egr stuff cause im getting crap for gas milage in city and highway. and a crappy idle. im not getting a code. but i figure it can't hurt anything.. but what all do i need to replace? like how many parts are there? i know there is the EGR valve itself. and then when i look at the autozone website. it shows an EGR time relay or whaver. and its like $80.. plus the EGR valve itself. which is $50.. do i need both of these? or do i just need a new egr valve?

EGR valve: GM# 17113483 AC# 214-5562
EGR diagnostic switch(temp sensor) AC# 212-337
EGR vacuum solenoid: # ?

Im pretty sure thats all. I got a solenoid at Advance, the switch for gmperformanceparts.com, and the valve from Vandevere. I replaced these things for the same reason as you and Im sorry to say they didn't help.