Help????

I have a 1991 safari xt with the normal 4.3 v6...approx 350,000 km , starting to have a problem, starts fine little bit of a rough idle , and on excelleration it starts to bog ,recent work, have done the plugs (no wires) pcv , o2 sensor, exhaust will replace air filter as i just removed it and it smells like gas and has black deposits ... what do you guys think might be causing ....thanks :banghead:

change the wires
I have a 92 Safari that did the same thing. Come to find out the wires were bad and sparking on the block.