2009 Kia Sportage P0501 Code: Fuel Misses, Jerking, Power Loss - VSS or Wheel Speed Sensor?

I purchased a used 2009 Kia Sportage with an I4 engine and automatic transmission (LX model, 125K km). It ran fine for at least 1.5 hours without any issues during initial driving. After passing a transport, the vehicle began exhibiting symptoms of fuel misfires and jerking—possibly due to erratic shifting or transmission behavior. I managed to drive it home safely but noticed significant performance degradation upon arrival. Upon inspection, the car displayed a P0501 diagnostic code. I initially ordered a replacement vehicle speed sensor (VSS) for installation the next day. However, after driving around briefly with intermittent misses and jerking, I took it onto the highway and drove for about 10 minutes. During this time, the engine began losing power—acceleration was extremely sluggish. The symptoms included small, sudden surges in RPM that would jump from idle to approximately 1.5–2.5 thousand RPM before dropping back down again, even when the accelerator pedal was fully pressed. This behavior suggests a potential issue with either the vehicle speed sensor (VSS) or wheel speed sensor, but I'm unsure whether it's one of these components or if there could be wiring faults or other underlying causes. Given that the P050 or VSS code is related to speed sensing and engine control, I'm seeking clarity on whether this points more directly to a faulty VSS (main speed sensor) versus a wheel speed sensor, or if it might stem from a wiring issue. I'm currently frustrated and looking for expert input. Any insights into diagnosing P0501 in a 2009 Kia Sportage would be greatly appreciated.