Briggs and Stratton - starts dying out when throttle is moved lower - Video/images

[cpt_cam]

Hi everybody,

I'm new and at witts end. I have a lawn mower that was left behind when I bought some property. I actually got it running which is amazing in itself but it dies out when I move the throttle "from the rabbit towards the turtle" on the throttle. It runs fine when I leave it at the top (which I assume is full choke).

Here's a couple of videos I made of the situation below. Notice how it starts dying out and the little flapper doohickey starts flapping as it dies out. I'm guessing that means it's not getting enough fuel or something? It should have plenty of air because I took the air filter completely off.

I had let the engine run for about 2 minutes or so to get it warmed up. I've replaced the spark plug, removed the belt for the blade (so the spinny part under the engine can spin freely and take the deck out of the equation)

YouTube Video 1 - https://www.youtube.com/watch?v=gdHGtIED4VA
YouTube Video 2 - https://www.youtube.com/watch?v=n5J1cL5PaQs

What would you recommend I do next?

Lawnmower: Craftsman 917.287140
Engine: Briggs and Stratton Intek 540cc 21 HP

 

[Mikel1]

Fuel system needs to be cleaned since it has been sitting up. This includes the carb.