my truck hates me,carb problem ?

[chainsaw]

Finished my engine swap, ran fine for two days, now wont stay running. 350 with big cam, 750 double pumper, hei , dont know anyother specs on engine. Acts like its flooding, have to hold it to the floor to start, sputters then cleans out and runs smooth for about a minute then sputters and dies.If you keep the revs steady at about 3 k, same thing runs smooth then sputters and dies. It looks like gas is dripping in the primaries when engine is off. Is that my problem? I'm NOT an engine guy,I did paint and body back in the day so I dont have any tuning tools or skills other then a timing light. It would start at the touch of the key without giving it any gas yesterday. Sorry for rambiling on.