I havent yet read the entire post but I will tell you this. The wires your pointing to are for telling the computer if the EGR valve is open or closed. If you unplug it... it will disable the resoginator valves (Flaps) in the intake manifold and throw a few codes.

If you are getting bucking while the car is just cruising around 45-55 then you Flaps are must likely gummed up. If you research "Breath of fresh air" I discuss the disabling of the egr and also the clean out of the Flpas