Engine Performance problem
2001 Chevy Blazer 6 cyl Two Wheel Drive Automatic 147000 miles

2001 Blazer 4.3 v6 147000. Intermittent cold start problem. My truck is hard to start maybe twice a month in the mornings. It is especially hard to start after rainy, humid weather. It turns over, then immediately sputters and dies out. If I press the accelerator during starting, it will sometimes eventually start, after softly backfiring in a few attempts. Yes, I do smell gas, but no black smoke is apparent. I have had the plugs, wires and cap changed. I have replace the fuel pump, filter and spider-piece (injectors). After it starts, there are no more problems for the rest of the day. It runs great. Gas Mileage sucks though. It used to emit a raw smell which my mechanic suspected to be coming from the catalytic converter. No other symptoms though. What gives?!