91 Silverado TBI problems

[texastruckjunky]

I have a 91 Chevy 1500 with the 350 700r4 combo. having problem with black smoke coming from the exhaust. Pipes are cut off after the muffler so it's leaving a black residue all over the rear end. But that's not the problem, truck spits, runs rough and dies, it's hard to start after words. If I let it sit for 30 to 45 minutes it will start. It runs for a little while then dies again. I've changed the fuel filter, fuel pump and rebuilt the TBI. Now black smoke is coming from the exhaust. And it's even harder to start. I've done some research on the problem and from what I'm understanding, it could be a O2 sensor or the MAP sensor. Any help would be appreciated. Thanks.