Please help. My Chevy 5.3L engine will not start or run

Until Yesterday this truck has run awesome!  I have done regular tuneup's, oil
changes, etc. etc. etc.
       Yesterday I left home and a mile down the road the truck started to stall.
like it was not getting enough, or way to much, gas  If I pushed the gas pedal
down further it would stall even worse. I stopped and looked at everything   
Started it back up and drove a block, then parked and kept it idling. After
about 5 min or so it completely died, and would not start again. (For the
moment anyway)
       I was thinking fuel filter,  because when I first turn the key, right over to
just before starting the truck, I can hear the fuel pump "load up/prime".   So
after doing that five times it started up and I drove half a block to the part
store and then back home, it died twice on the way home, but I made it.
       I replaced the fuel filter, turned the key on and off 5x to "prime" the
engine. And from then on the truck would not start at all! I tried starting it over
and over, waiting a while and then over again.  Nothing.
I took the plastic "vortec" cover off, and removed the fuel pressure regulator
to see if gas was getting there. The bar was completely filled with gas.  So I
am assuming the one on the other side is the same. I am also assuming the
fuel pump is fine since there is plenty of gas getting here!(???)
I hope that is enough details. It's definitely not spark plugs or start plug
wires,(?) because it does not start at all. And no misfiring when it was running.
Maybe the distributor???
Anyone have an idea of what the problem may be?

Thank you.