94 k1500 stumbles when warm

[bones001]

1994 K1500 5.7 TBI automatic. When warm the motor will run very rich, causing it to flood, or stumble when trying to accelrate. Checked CTS, MAP, O2, and IAC sensors and all are within spec. Timing is set, no vacume leaks found, and just changed fuel filter, fuel pressure regulator, rotor, dist cap and plugs. No blockages in air filter, or air system. Once motor stalls gas must be floored to get it restarted, and get large black cloud from exhaust pipe (did check exhaust system and found no blockages). I can't find anything wrong in the fuel enrichment circuit that would cause this, any thoughts??????