Check your transmitter settings.
For the travel:
- Make sure the Dual Rate (D/R) is not turned up, it will limit the travel.
- Check to make sure you End Point Adjustments (EPA) are correct. This will also limit the travel but differently in each direction.
- Check the Steering Trim to make sure it's centered
- If you have a subtrim make sure that is also zeroed
For the speed:
- Makes sure you have only one ESC powering the receiver. Your description sounds correct.
- Basically search for "Steering" in your transmitter manual.
- Some transmitters have Steering Servo Speed Delay (STSPD) features. This cause it to ramp to slow down and become laggy.
- If you have a steering curve, make sure it's doing something weird.
- If you have a Mix feature make sure it's turned off.
- Make sure you have enough Amps supplied to the system. The ESCs should be a pretty small load
- Check (verify) the voltage on the BEC. Get a multimeter and see what it's at.