Briggs & Stratton 500 CC 17.5 HP engine surging and misfiring

[semimechanicman]

31R977-0027-G1

I have a 17.5 HP b&s that surges badly and occiasonally makes popping noises. I switched out the carb with a new one to see if it was that but it also surges (it is chinese) and pops. The old carb also surges and pops. It surges a lot more when the blades arent off, when I turn them off you can hear that it gets a little better but it still doesnt run smoothly. Is there any carb adjustment on these type of carburators? I tried adjusting a silver screw in the front of carb but it didnt affect much at all. I could use a few ideas and also the spark plug I have not changed but it looks pretty new anyways.

Photo shows the screw I moved. (Same exact carb)

 

[StarTech]

I recently had one these Nikki clones that idle mixture jet was under sized and no matter how far you turned out the idle mixture screw it had no effect. I ended up having to resize the idle mixture jet.