It would help greatly if we knew the craftman tiller number and the make & number of the original carb.
Also the fuel filter type
The felt filters can shed fibres with is why the felt bit is held on with a clip so you can remove it & clean the gauze strainer underneath.
Also once felt filters get contaminated with water they will no longer pass fuel properly and should be replaced .
If the carb has 2 fuel lines then they could have been transposed so you are trying to suck fuel through the return line which most times is above the fuel level.
A bad fuel tank vent can also couse these sorts of problesm.
Finally there are a lot of QC reject carbs out there being fobbed off as "OEM" or "Fits a " or "Replaces A " that are faulty, bought as srap metal then resold as a functioning carb .