Lump tickover & smoking out of the exhaust... help?

[James H]

Recently picked up my s12, she had been sitting around for a good year without any driving, anyway drove her back to my place (say bout 8 miles) & she was fine got me home fine, was ticking over really smoothly once i got home so got her up my drive & jacked her up in prep for me working on her. She had been sat up my drive for a week without being driven so thout i should start her up & let her run for a while, but once i did she was running terriable idle was so lumpy & was really dirty coming out of the exhaust.... what do people think my be up with her & what can i try to get to the bottom of the prob?

Help please, thanks James