When configuring a Doppler-eliminating optical path, the residual Doppler frequency shift in a cascaded three-level thermal atomic four-wave mixing (FWM) process is typically ignored. However, in case of a substantial wavelength mismatch between the probe and coupling light, the residual Doppler shift can considerably impact the FWM process. This study investigates the effect of the residual Doppler frequency shift on self-dressed FWM in a ⁸⁵Rb hot atom D₁ line system. By varying the coupling field strength, it is determined that the observed bimodal structure in the FWM spectrum corresponds to Autler-Townes (AT) splitting. These AT splits are primarily attributable to the residual Doppler frequency shift of the two-photon resonant atomic group. Further, their separation exhibits a dispersive distribution relative to the coupling light detuning, which increases with increasing coupling light intensity. The findings of this study have potential applications in the measurement of the Doppler frequency shift of optical fields and the incoherent attenuation rate of thermal atoms.