if its an old pre emission model
try taking the carb apart and clean it out
if it has an o2 sensor do not take it apart

also on pre-em model
it should get about 1.5 - 2 lbs of fuel pressure at teh 1/4" pipe plug on the regulator (impco cobra or jb2)
more or less and its not gonna run right
usually on of the diaphragms get a tear and flood the system and you get hard starts and other issues
to see if its flooding take the vapor hose off the carb and let a lil air in while you crank it
if it starts right up and or you can get it to smooth out that way
the regulator is bad
also if it has a vacuum lockoff
once or twice ive seen them go bad and pull fuel through the vacuum line into the carb again flooding the engine
so check that too

itd help to get the serial number too

also new models with emissions
the fuel pressure dosnt feed the carb
the updraft from the carb turns the regulator on
so make sure your vacuum is good