my vectra dies?

hi, i have just done the head gasket on my 95 vectra along with the inlet/outlet gaskets. the car idles fine but when using moderate amounts of acceleration it just loses the power but doesnt cut out. i removed the plugs to find black sutty deposits [dry] which would lead me to believe that there is fuel mix problem, but only since the head was of. the choke is working fine and the air cleaner isnt to bad. any ideas guys. thank you