it is a 4.3 fiooding

If your 4.3 is a vortec version,it has a fuel distribution unit inside the intake plenium,some refer to this as a spider because it has 6 plastic lines,one to each cylinder. They get brittle from the heat of the engine and crack or break open. This is a dealer item and cant get it from most part stores. You may get lucky and find one used and in fair shape. The fuel pressure regulator is also part of this assembly,and can be the problem also. The diaphram can bust and flood the engine. To replace it you have to buy the entire unit or as I mentioned,find a used one. Thing to remember is,a used one may be as old as the one you have, so check it out and make sure the lines arent cracked or brittle.

check your fuel pressure regulator inside the plenum also the two fuel return lines inside plenum also before checking the spider

VIN 'W' engines can get fuel leaks at several places. Most likely are the fuel pressure regulator which you can buy at NAPA for $65, or the rigid plastic lines (the 'Nut Kit') leak near the back corner. The 'Nut Kit' is also about $65 at NAPA, but you will have to remove and replace the intake manifold. (If you do that, get an EGR screen.) Look inside the upper intake for areas washed clean of oil and for gasoline puddles. You can get a complete rebuilt injector assembly for under $150. Check the Web. I have done all this myself. I know firsthand.