318 hesitation when cold

Here is a photo of the choke when the car is cold started.

Here's what it does. When I give it a quick rev, the choke plate almost closes, and the engine sounds like it stops for a split second. Then the choke plate opens back up and it idles normally again. After doing this several times, it looked like the choke plate opened up a tad more, and then it stayed and didn't close anymore when giving it quick revs. What could this be?

choke.jpg