my car still giving me problems

ok so i have been working on this my 85 rex carbed for about a year and a half i got it running but it wont idle you have to keep it reved pretty hight to keep it running. the seal between the carb and intake is good...and the vacuum lines are as good as they can get....could the O2 sensor play into the reason why it wont idle? any suggestions woudl be great