Based on the far off-resonant four-wave mixing process, the slow light propagations of the amplified probe and generated conjugate pulses are obtained experimentally. Simultaneous manipulations of group velocity are realized by changing the two-photon detuning between the pump light and the probe light. The dependences of gains of the injected probe and generated conjugate light on the one-photon detuning for continuous wave mode are studied at different cesium vapor temperatures and pump light powers. It is shown that the maximum of gains occurs at the proper Raman one-photon detuning. The dependence of delay time on the two-photon detuning is measured using the 6 μs and 365 ns probe pulses, respectively. For the 6 μs input probe pulse, the maximum delay times of the probe and the conjugate pulses are 2.1 μs and 1.9 μs with the fractional delays of 0.35 and 0.32, respectively, corresponding to 0.000119 c and 0.000132 c group velocity. The high fractional delays of 2.07 and 1.83 with the maximum delay times of 756 ns and 670 ns for the 365 ns input pulse are obtained.