Car stalls often when I step on gas

I am a little vague on somethings. The throttle plate is located in the air filter assembly right? Where would iac hole? Thanks.

Ok, found it already and took it off top of intake manifold. Real easy to get to. I cleaned plate, inside throttle body by moving spring mechanism back in forth and got alot tar gummy stuff off. I used throttle body cleaner from auto zone. Put everything back together. I drove to take someone home and did not have any problems. Gmc jimmy ran smooth even though I noticed gas pedal went down easy and there felt like a lose of power, but ran fine nonetheless. Today, being sunday I got up early and change my fuel filter and gassed up. There was few times I had to crank truck more than once to start and stalled/sput when I stepped on gas for a few secs and then it would go hard. I thinking to just go ahead buy fuel pump and replace it. If it was a relay. Wouldn't check engine light come on and fuel pump will not work, thus car would not start, right?

Yep, I just order a fuel injector pressure gauge to test my psi on fuel test port. I will post results.

Yes, I know. Over here I get round around alot so I order one and got today. I hook it with know problems. I got 60 psi with engine running and when I turned off engine it went to 0. I saw some videos that said "your bleed down should not go to low". If so, maybe I am missing a o-ring when I change the fuel filter or something. Plus recently, when starting up it takes a few extra cranks to start and when you step on gas it feel like it is stalling and there appears to be knock sound coming from rear underneath car. Then it take off fast. Thanks.

Could I test the fuel regulator or just replace it. Is it easy to replace?

Forgot to include, wouldn't check engine light come on if it was fuel pressure regulator?

I replace fuel pressure regulator. When turn engine on afterwards it backfired from engine area. I did use throttle body cleaner on "Idie air senser" and around intake manifold. When drove to fill up, it rode smoothly. But once after fill up, than startup. It backfired a little bit. Than took off. I checked pressure with engine on and cranked up. The psi was at 55 to 50 and it would not hold. I check again after returning from gas station same thing. I did feel instance where they felt like lost of power when step on gas. I have "CSFI" system so it was not easy as you stated in your early replies. But I changed out old fuel pressure with new one. What would be, next course of action.

Doing these check means I have to take fuel pump out right? If so, I should replace pump anyways, right?

I forgot to include some pictures. These have iac cleaned, fuel injector spider; which now GMC recommends updating to "MFI" system. Fuel pressure regulator old and new.

I can hear pump kinda loud when I turn on engine too. I will take my chances on replacing it since I don't want it to go out on me and I am not so fimilar with testing it (except pressure which is lower than what you said). I am looking at after market pumps now since they are way cheaper than OEM. Once out of fuel tank, can I use same connector or do I have to splice wires and replace with new connector? Also, once installed and not attached car. Can I turn engine to on position to see if new pump is operation before installing all the way on, that way I don't have to do this job again? Thanks.

I ordered pump and will be getting this week. I forgot to ask "is it safe to drain a portion of my fuel through strata valve on fuel line with fuel pressure gauge by pressing pressure relief button with see through bleeder hose into gas jug"?