Quadrajet won’t idle

I have a question for you guys regarding a Bayliner with a SBC 350 and a quadrajet carburetor. The carburetor was replaced with a rebuilt one off of ebay because the old carburetor had a sticking float and after being on a boat that stays in salt water year round we decided to just replace it. But anyway the boat starts and revs well but as the engine warms up the rpms drop way down and it idles very rough. If you close the the choke slightly though the boat runs fine and revs very quickly. Obviously I am going to try to get a replacement carb but that may be tricky since the company is in CA and the carb was bought off of ebay. Any thoughts on what might cause this? Thanks.