In recent years we have witnessed many breakthroughs in the field of graphene nanoribbons. The promising features of these structures have created new opportunities in manufacturing electronic devices. However, due to the low precision of synthesizing procedures, process variation is still as a concerning challenge in developing nanoscale devices. In this paper, we have theoretically studied the impact of process variation during the progress of Boron/Nitrogen doping, strain implement, and antidote insertion. Our study will focus on Armchair Graphene Nanoribbons. In order to investigate our results, simulations using the MATLAB tool, tight-binding approach, and Monte Carlo method have been carried out. Our results demonstrated that the vertical doping method is the most reliable approach in compare to others. This approach also provides tunable band gap size in a wide range, allowing its usage in future nanoscale devices.