I may be totally wrong but I've never heard of your EGR valve causing your car to buck. Can't happen. But what it can do is melt the wiring on the side of your block.


So if you unplug it it isn't getting hot. Maybe it hasn't burned through your wires yet, maybe it's just melting the insulation and allowing the wires to rest on the pipe and grounding them out. Then when it cools it's seperating from the pipe.


I'd check the wiring below and around your EGR pipe and see if it's being melted or disfigured...then you can get to the real issue.