1968 340 AVS 4425S carb problems

We checked for vacuum leaks yesterday and didn’t find any. We got gas a couple of days ago with no improvement. I did take the air cleaner off and covered the top and the rpms went down like it should, this makes me believe there is also no vacuum leaks we did not spot. We are going to buy a rebuild kit and make sure all is good on the inside and try and free the screws for I think they are frozen in place. When we do rebuild and try and get it running better (hopefully) I will give an update.