1991 Chevy Silverado flooding

I have a 1991 Chevrolet Silverado 350 automatic 4x4 with a thottle body fuel injection. This vehicle floods out and is very hard to get started. It appears to be dumping alot of raw gas into the throttle body. You must hold the gas pedal to the floor to get it strated. Once strated the idle is very fast and you can drive the vehicle but it wont idle, it will stall and is a pain to get started again. The smell of raw gas is very noticeable. Once vehicle gets started it also blows out black smoke out the tailpipe. (Just the aw gas burning off. Occassionally the vehicle runs fine but not often.