Carburetor issues??!? Or something else?

[30aadoodlebug]

So the title of the post says it all. I went out to start my truck the other day, and the strangest thing happened: it wouldn't idle. In order to make the truck continue to run, I have to pull the throttle level down to bring the engine up to around 4000 rpm. The truck was running fine last week when I put it away, and now I have this issue out of the blue. I have done the basic troubleshooting: closed the mix adjust valve via the choke rod and opened it to where it should be on a Zenith; putzed with the needle valve a bit to see if that might be the issue; and lastly sprayed crab cleaner into the carburetor to see if it was just dirty. Les Andrews book says that it could be the float being to low, but where it was running perfectly last week, I don't think this is the issue. I put this carb on this past June, and it is a fresh rebuild from a well-known reliable shop.

Any thoughts would be much appreciated!

Jon