I'm sure someone with a lot more expertise than me will give you the nitty gritty but from what I can see the EGR valve seems to be pretty critical for your vehicle, What is the EGR valve and what does it do?http://autos.yahoo.com/maintain/repairqa/engine/ques080_1.html
http://autorepair.about.com/od/glossary/gr/def_egr-valve.htm
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