Mercury

I have a mercury mountaineer 2000 5.0 and the cheak engine light came on we put a hand held computer on it and the code said egr flow insuffucent so replaced the egr valve and the light came back on again you can feel the truck bucking kind of going around 35 to 40 mph could it be a oxygen sencer or what."

This is what happens when you use a code reader. you get a code for an egr valve and you think you need a new egr valve. usually you end up being wrong. i got a p0700 transmission fault code on a caravan today. does that mean i have to replace the transmission?