I think you are just trying to move the character in the same direction every time they press a key right?
Check this guy out:
When this Launch Character fires it will send the character 40 units into the air and 800 units to the left. If you want them to go to the right then it would be positive 800 instead of negative 800.
If you want them to go forward then it will look something like this (backwards is a negative number):
The only reason I suggest sending them slightly into the air is that if you launch a character that is on the ground then they are still affected by friction and won’t be launched as far. I also override their XY and Z velocities so that if they are already falling then it lets them “dash” in mid air.