Put a small hose clamp on you tube that goes thru the fan shroud. It will keep in place while changing the throttle cable. It will leave one hand free to do if your in the dark with a flashlight. Just tight it down on the backside and leave it. When you push the throttle cable thru the tube it wont move on you, the hose clamp will hold it against the shroud. It will be there for you when you need it. Old trick many may or may not know but its a good one.

... better yet, when you change the cable buy a sink water supply line made of PVC. Pull the metal tube out and lay it aside. Trim the water supply line a bit longer in length than the metal one and place it back through the fan shroud till the swedge on the end rests against the shroud. Slide under there and put the hose clamp or a zip tie on the end that comes out past the front tin.

This upgrade will make your cable last much longer, and it wont slip in through the fan shroud like the metal tube can.