I've never been able to run on parkour maps. Especially when I'm moving my arms. Is there something that I'm missing?

As much as I know this isn't what you want to hear right now, it's mostly just toiling away in Singleplayer until you get the hang of it. Knowing the basic run is a good jumping-off point, but as I'm sure you've discovered, that shit doesn't work on most mods. Try to keep it simple until you can at least stay on your feet, and then try and move into making it look more complex or realistic or whatever you're going for.
The problem I had when I was first trying to learn how to run is that I would always pitch backwards after about the 3rd step and fall flat on my ass. Make sure to try and keep your tori leaning forward to keep your center of mass in front of you, and use shift+space if you aren't already. It's shitty I know, but if you just keep going at it you'll get it eventually.

That helped, thanks.