2004 Silverado 1500, 4.3L V6 2WD (120000Km)
I have this cold start issue, only showing in first start in the morning (or when sat 10-12hr), more when is cold, less when is hot.
My truck always start on at the 1 or 1/2 crank and now take 3-4 cranks or a second attempt to run, the rest of the day start at the first touch of the key.

I alredy made a lot of Research/Check parts and I am convinced is a fuel issue.But I need another opinion before spending another cent.
I have checked Cap, Rotor, Oil Sending Unit, Wires (new), Spark Plugs (new), Coil, Fuel Pump and Filter (new), Injectors (pressure cleaned twice), ECT sensor (new), IAC valve (cleaned), MAF sensor (cleaned), Air Filter (new), Cables and Battery (charged and tight/cleaned), all this parts are fine, No Trouble Code have been set.

The engine runs smooth, no rough idle (only high idle until warm), no stalls/backfires/misses, no black smoke from tailpipe, the plugs was little blackened (fouled) before be changed, I dont smell fuel in the oil dipstick, No Gasoline Dripping out of the tailpipe, Only smell a little bit of raw fuel in the first 5 seconds when the engine start in the morning (only morning), Gas mileage go down (1 or 2 minus) and Little Pinging or Knocking Engine sounds during full acceleration or high uphill and I feel a lack of power on full acceleration (but is a feeling).

Personal Conclusions:
1)Thinking is a bad Fuel Pressure Regulator (low pressure or small leaking)
or
2)Bad Fuel Injector Spider Assembly (small leaking)

What can be the real problem?.
What kind of spider assembly my truck should have? SCFI or MFI?.
The upgraded Spider assembly for SCFI Vortecs apply here?
Or just a FPR replacement?.


Thanks for the HELP