my van pushs black smoke when it going up a steep hill and i get a black spot on my driveway when its idleing. It is a 2 barrel carter, the metering rods are set all right, the float level looks ok. The van runs good but is hard on gas.the choke works its wide open when the motor is warm

hows the spark plug color? if black or dark brown maybe fuel mixture
too rich.
since choke open when warm, float level ok, then maybe there is
some air restriction in air cleaner.