The random replacement interaction-by-exchange-with-the-mean (IEM) model, which was proposed previously as a numerically more preferable IEM scheme, had been employed for investigating the micromixing effects on the steady-state multiplicity and the relative stability of the oscillatory and stationary state of the Gray-Scott model (Gray, P.; Scott, S. K. Chem. Eng. Sci. 1983, 38, 29). In the bistable region, incomplete micromixing tends to largely reduce the attraction basin for the thermodynamic branch, while in the region where the stable limit cycle exists, it tends to weaken the relative stability of the oscillatory states. Owing to the tandem replacement nature of the present micromixing model, a stochastic response behavior is observed for the resulting limit cycle attractor and the attraction basin boundary on the parameter space.