Results are presented from a three-dimensional (3D), nonlinear, resistive magnetohydrodynamic (MHD)-code study of thin shell modes (TSM) in a reversed field pinch (RFP), when toroidal plasma flow is introduced by adding a drag force in the toroidal momentum balance. Without this rotation-inducing force, TSM wall-locking develops and the loop voltage and edge magnetic fluctuation level are increased compared to the conducting shell case. Inclusion of drag on the plasma which produces toroidal flow in turn creates a force on the mode perturbation. Above a threshold drag force wall-locking is eliminated, the perturbation rotates and the loop voltage and edge magnetic field fluctuations are reduced to the value of the conducting shell case.