92 s10 blazer with 4.3 cpi. I have replaced fuel pump, injector spider, fuel in and out lines, spark plugs, wires, rotor and cap, ignition module, ignition coil, cat. converter, tps, map, iac, radiator, thermostat, hoses, o2 sensor, air temp sensor, air intake hose all just last month. It ran good except idled alittle high but yesterday it started blowing black smoke out the tail pipe, any ideas.