mopar won't stay running with carter 625 .

:hello1:just installed a Good used carter avs 625 cfm. problem is......... it will not stay idleing .. have to hold the throttle on to 2000 rpms in order for it to run .. and it runs real bad like it is dumping gas down the carb. But it is not dumping ! Could this be a vacumn leak ??
Installled a new gasket when installed carb but is was a very thin cheap gasket.. anyway > I took the carb off and clean it, blew everything out and rebuilt it and installed again and still did not want to idle. any ideas ?? Thanks so much !!
:banghead ::help ::-k:dontknow: