rough idle and abs light
 

hey,
i have a 1995 2.2 cavalier automatic. it has a rough idle at start up and persists to be rough the whole time i drive it. its fine on hwy but as soon as i let go of the gas to hit the brakes it wants to die. i put new plugs in it and i noticed plugs 2 and 4 (counting left to right looking down at engine when standing in front of it) are blacker then the other 2 which are a nice brown. i checked spark by pulling one plug wire at a time while it was running and put it near metal and seen the spark jump to all the plugs and they seem fine. it smells like its running rich, everytime i rev it up it shoots black smoke out the tail pipe which smells rich. and also my abs light is on and i have no abs. i checked the fuses under the hood and there good. the brakes are hard to use under low speeds but as soon as u get it up to 50 and above they are easy to puch but still no abs just solid brakes. is there anything to check for? are cylinders 2 and 4 run off the same ignition coil? would a bad brake booster wreck the vaccum of the motor and make it run bad and also throw the abs light on? any ideas?

thanks in advance any help is appreciated.