I have been flying the 737-600 and 700. The problem I have happens with either one. When I am landing and the front wheel assembly touches the groud, it starts swinging left and right. the plane becomes almost uncontrollable. Once I get it off the runway and stop for about 30 seconds,it works fine. I am using a set of CH pedals. This happens if I have the pedals plugged in, or unplugged. Dave

Maybe you center of gravity is too much to the back of the plane? If so, move passengers and cargo to the front.