@candymarie Have you adjusted the carburetor after replacing it? Most carbs will require adjustments to run optimally. There’s a high (H) and a low (L) screw that needs to be tuned.
There could be an air leak somewhere (most likely in a fuel line) or in a gasket. Inside the tank there is also a fuel pickup filter that needs to be replaced as they easily get gummed up. I’d also change the fuel lines as they can rot and cause air leaks.