Adding momentum to a character's movement

Hi

I have followed a tutorial for an earlier version of unreal regarding adding momentum to a character’s movement. https://www.youtube.com/watch?v=eA2jPrhAHK0
Am wanting a charcter’s speed to increase over time but then return to normal as soon as stopped and have to rebuild up again when moving again.
This worked fine in the earlier version of Unreal and had successfully applied a clamp too to limit the speeds… but now I am using enhanced input mapping I am struggling to work out how to apply the same nodes. Currently the momentum is working in all directions and the clamps work too, but I am really struggling to get the momentum to reset back down after the character stops moving. What is happening is that when the character stops running and restarts movement there is a brief walk for a fraction of a second but then it jumps straight into the top momentum speed last used. I’d like the momentum to return back to zero everytime the character stops moving. Any help or demos much appreicated.