its a b16 in a crx and when i go to start it up it idles at around 3000 rpm and when it warms up it stays at 2300-2500 rpm. Ive cleaned the iacv valve, played around with the idle screw, checked for vacuum leak and its still the same. also when i disconnect a vacuum hose that goes from the map sensor to the throttle body the rpm drop to 1000 rpm but it spits out black smoke.i don't know what else to check if some one can please help, thanks in advance.

 

bad ground?
throttle cable stuck/missing spring?