Help.. Bravada is hesitating

I recently purchases a 1993 bravada v6 4.3L. My problem is when i start it up, it runs decent until it has warmed up. It then bogs down when i punch the gas, but when I lightly push on the gas, it will some-what accelerate while cutting out from time to time. Also when I punch the gas sometimes you can hear a backfiring coming from the air intake. I have put on a new cat and knock sensor since that came up bad on the test... but it is still doing the SAME thing. Also.. when i start the car you can see a large amount of exhaust coming from the tailpipe. All of this is leading me to think its with my fuel system, but what part of it i dont know. Please... if anyone has any suggestions i'm down to hear them.

There's a black cap on the fuel line at the drivers side rear of the intake manifold. Take the cap off to access the Schrader valve then connect a fuel pressure testing device and look for between 50 to 55 lbs. pressure....anything less is likely to be a worn out fuel pump or clogged fuel filter. If you run these out of fuel the pump will wear itself out quick as the fuel lubricates the pump.
After testing the pump by turning the ignition key on, it'll stop itself after a coupla seconds THEN the fuel pressure should hold steady for a coupla minutes although a good system will hold that pressure for 15-20 minutes.