My 93, 4.3L CPI Engine W, for the last 8-10 months has given me much grief.
I idles rough and hesitates at takeoff. I blows out black smoke if I step on it. It also smells like rotten eggs. I have replaced the fuel filter, the timing chain, the spark plug wire, put in double platinum plugs, an Oxygen sensor, the distributor cap, the rotor, the modulator, the EGR valve, the MAP sensor, the throttle position sensor, cleaned the air induction with Berryman's B-12 . . . . . . . . Anything else I should try? It stinks and hesitates still. Maybe the catalytic converter?

Broke and confused

if you live in a state that does vehicle inspections don't do this remove the catalytic converter and replace it will a piece of exhaust pipe