Spark plugs fouling alot

Does anybody have any idea why all 3 spark plugs on the drivers side of my 4.3 cpi vortec engine could be caused by i checked the wires replaced the plugs yet they still foul as the other side sits and smiles. and i know that the new plugs fire so its not a coil. Thanks

I'm gonna say you have a leaking FPR (fuel pressure regulator).  You'll need to verify an internal fuel leak by doing a fuel leak down test with a pressure gauge first, but I'm betting on a faulty FPR.  You can also pull off the plastic cover on the top of the engine, then you should be able to unbolt a cover and have a look inside.  If you see pooling fuel on the lower intake, you've got an internal fuel leak.