Is there a way to globally increase the height and lower other nodes at the same time?
How do I raise/lower a node and it stay in it's same place in the timeline?
 
It's a wah envelope but the sweeps are not deep enough or high enough. I have the nodes exactly where I want them, except for the height and depth.

Depress-n-hold the 'shift' key on your keyboard--then the mouse cursor will commit to the action it first carries out.
e.g. move up-down--will be the only action performed whilst the 'shift key' is held.

In addition, to change the whole  envelope make sure nothing is selected**. Move the smart tool toward the top third of the automation lane. The smart tool changes to the "level" mode. Click drag up or down and the whole envelope as well as nodes move together.
 
** You could also select the whole envelope but I prefer "nothing selected". It has exactly the same affect and I personally find it easier to ensure that the whole envelope is affected. In select mode it's possible to accidentally have a range selected hence only affecting that range.
 
HTH

As I read it you want to raise the peak nodes, and lower the valleys. To do that, right-click and sweep to lasso all the upper nodes, then Shift+Drag (with left-click) one of them up to raise them all. Then lasso and Shift+Drag the lower ones down the same way. 

Yeah. Brundlefly has nailed it. I've misread your post. Sorry.

Excellent! Thank you very much!

Just tried it and it totally works! What a time saver!
 
Not to clear the snow away. :-( At least it's light snow today.