Just can't steer this airplane

I recently downloaded this file, PiperArchrIII.zip, from Simviation. The plane handles fine in the air and is nearly impossible to taxi in a straight line and any speed. Take off is a battle to keep on the runway until finally airborne. I've set the realism to easy and even tried coupling the rudder and airlerons but nothing works. Does anyone know of a setting or addition to the config file that could improve ground handling?