<p>This manuscript explores the coherent manipulation of the surface plasmon polaritons at the interface of a four-level dielectric medium and gold metal through the effect of Cross-Kerr nonlinearity. The study examines how the SPPs sensitivity can be significantly influenced by both the driving and Kerr fields, with additional dependencies on the diffraction order and grating period. The sensitivity is shown to vary as a function of the phase and the Rabi frequency of the control field. The findings indicate that the maximum sensitivity reaches up to 4000 deg/RIU with control field phase, while minimum sensitivity is recorded to 350 deg/RIU, associated with varying Rabi frequency. These results present valuable applications in fields such as optical tweezers, plasmonic technology, and sensing techniques.</p>