carter avs 625 will not stay running ..

I have a carter avs 625 carb that was sitting around for a little while ... nice shape good pump nothing cracked etc...Problem is when I first installed it It started and ran fine on high idle and when I knocked it down off high Idle and got into the secondaries it then died .. everytime I start it it will NOT idle . I have to hold the idle up 2000 rpm to keep it running and it is running real rough at 2000 rpm.. so and I take my foot off gas it will die everytime.. I did install a new base gasket when installed but it was pretty thin. I rebuilt the carb and installed again and still would die at idle... I'm thinking maybe a bad thin base gasket..
Soon as I installed the original carb back on that carb ran fine... I checked the needle and seats > they looked fine and float also.. No fuel is dumping in the carb while running either.
sound to me like a big vacumn leak... any opinions would be appreciated.
Thanks !