Something I found myself constantly trying to do is to

1. sprint via holding spacebar
2. release
3. then quickly tapping spacebar to jump

This of course doesn't work out well, you go back to your default running speed almost immediately.

So basically what I'm trying to say is allow the player to retain is sprint speed for a split second longer (can disguise it as "momentum")

This would allow you to sprint, jump and grab with the same button (hold, tap, hold). It should also feel natural.

haha, dont release the space bar untill your in the air, but i agree and the top speed is reached to quickly aswell.

While holding spacebar, press "use". That triggers jump too.

Yeah, it's like DC said..

We will mention all these details in some kind of manual eventually...