Sticky throttle on 200 Chevy Astro
There was a recall on the throttle body blade on the 4.3 a few years back for the throttle body to stick in the close position. Yours being 9 years old makes me think that there not going to do anything for it but give you the solution to the sticky throttle blade.
The solution was to change the blade. You can try cleaning the throttle body blade by spraying throttle body cleaner in to the barrel of the throttle body. If you look down, you'll see the carbon build up and it may just need and good cleaning.
If that does not work, you can buy a new Throttle body blade which is only held on by two screws on the throttle blade shaft.
Start with cleaning the blade and throttle body with throttle body cleaner. Just follow the instruction and you'll be fine.
Keep me posted and good luck.