In the end, it seems that the answer was a combination of two factors:

• First, the application of some limits on the magnitudes that values may have.
  • i.e. Via the use of the "min" function to prevent values from rising too high
  • This being applied to both the main vector and the "direction of motion" vector
• And second, the application of a "friction" force, which opposes the main vector and thus dampens its value.