If your motor is indeed a stepper motor it wont run without a stepper motor driver. The 4 wires have to be pulsed on in sequence to control the speed and direction it turns. The driver board does that, it converts your FWD, REV & speed inputs into the appropriate pulse sequence.
Its no good using a 'H' bridge for a stepper motor, these work with the ordinary, permanent magnet & brushes, DC motors.
To test your motor if it is definitely a stepper motor, short all 4 wires together then try to turn the shaft by hand. It should turn somewhat harder, and jerkingly, like there was grit in the bearings.
Go to Google and search for stepper motor driver schematics & theory to read more about how they work. They are great for robotic applications but I'm not so sure about RC cars 8)