egr valve replacement/cleaning

first of all I have made alot of money on autozone misdiagnosis! nothing agianst you for trying to save money,at best just have them scan it then ask us here what the codes mean,or take to professional shop.either way I am happy to help!99.9% of the egr concerns are with the dpfe sensor out of range.you probable got a dtc of p0401 or p0402.if it is a p0401-egr insuff. flow. ground the egr vacuum regulator so that it pulls a vacuum on the egr valve.if there is very little to no difference in the engine speed your ports are clogged.you have to remove the throttle body/egr spacer plate.when you have it off you will see carbon stuffed in the ports,just clean out with a pick or something long and pointy.if your enginbe speed actually does go really low or almost stalls when you ground the egrvr then check the dpfe voltage reading.good luck,let us know what happened.btw- use a test light to make sure you ground the correct circuit!