Abstract: A power tool includes a fluidically-driven prime mover controlled by a multi-stage, throttle-actuated dual-ported mechanism disposed in the power tool. When the first stage is actuated, pressurized fluid is admitted into the prime mover via a first delivery path in fluid communication with one of the ports. When the second stage is actuated, pressurized fluid is also admitted into the prime mover via a second delivery path in fluid communication with the other port to augment the volume of pressurized fluid admitted into the prime mover via the first delivery path. In one embodiment of the present invention, the prime mover includes a dual-chamber air motor. Upon detecting an imminent stall condition, an operator can axially advance a trigger stem to admit a boost of pressurized air into the motor via the second delivery path.