My engine has no power why?

The pressure is 43.5 pounds. So is the pump bad?

Well that was a job but I did it. The ruck has never run better. Thanks to all who helped. I love this site.

The effects:
Lose of power/choking/backfires if I try to put the gas on. I have noticed I have lost major power anyways.
From this v8 now then when I bought it (used).

Before (cold start) no issues. Until the truck warms up after one hour? Driving, if I push the gas in to go hard, it has this BAM no power. Nothing if I force the gas in even when I know I am getting 0 power out of it, (feels like it goes into neutral) it has baby back fires. When I let off the gas, push in 20% it has some what enough power to drive down the street. So when I take off, or even go anywhere, I cannot push the gas in much or it will just choke.

Only way I figured out how to fix its self (before) was to just shut it off for few minutes. Then I found out I can shut it off for five seconds until computer resets and re start it - (before) I got power and no choking.
But now, even after two hours of driving, rebooting (shutting off) does not help 50/50 of the time.
It is getting worse after two weeks now?

Prior to this happening, I used to drive only in third.
Then I started to just drive in (D). Started to have check light come on. Then it goes off. Second time it came on got it checked out. O2 Position 1 and 2 sensor is bad. Then light goes back off. Only three times this has came on, no I have not changed them.

No, I have not did a tune up, or changed anything.
Not put any fuel cleaner in or nothing.

I figured out the 2wd/4wd issue.
After hitting bumps in the road and
all that. The darn plug wire was lose.
Took off the dash and pushed hard.
Never had an issue since.

For the gas/losing power issue.
No clue yet. With money problems
and time, I have not yet to fix it.
Very soon and when I do I will come back
and update.

Until then, I am thinking fuel pump again.
Or, fuel regulator might be it.
The whole choking is making me wonder.

No light is on. O2 only problem coming up.
Yes, I did get tune up done. Wires,
plugs, fuel filter, cap, rotor 9 yards,
Still no difference.

However.
He did clean my carburetor, that did seam
to help for twenty minutes.
I have bought five fuel tank treatments. Four carburetor cleaner and one Injector cleaner.

I have also noticed full tank, issue is worse then only having 1/4 tank.

My truck lost power while driving at 35-40 mph. It seemed to lose power for a couple of seconds and then come back for a few seconds. It did that a couple of times before it lost complete power to the engine and all power components. Is this likely to be the fuel pump?

Thanks for the help!

Ok, got it in the shop!
Paid 26$ for them to tell me my Cat*
Is ok. Nothing wrong with it. My fuel (PSI)
Is low. I think 50s? So I replaced my Fuel
filter. Black gunk came out. Still no fix!

Regulator on a 99 Chev Tahoe - No idea
where it is. But what I have seen it was dry.
The uh, Hose was dry. 55$ part I will be replacing
in few days. But still losing power and getting worse!

When I replace the GD fuel pump (250 part + 100)
and if thats what it is I will let everyone know.
And since iv been seeing about how shity this
truck is with the fuel pump issues, im guessing this
is what it is. But in time like this with money,
this will be hard to pay for. But im sure thats what
it is the whole time.

Yeah, I went to buy a Fuel pressure regulator.
Went to put it in, but yet I dont have fuel lines.
I found out I have the other type of engine.
SO.

I found out I have to take off the top man/fold
And thats going to take more money.
So.

I hope its just the Fuel pump. And im thinking
it is and it would be cheaper at this point because
from what I hear Fuel pumps go out on these trucks
a lot for some reason.

Ok. So my cable went down the day before I fixed
what it was this whole time!

I was correct the whole time!
Fuel pump. FUEL PUMP! OMG! DAM FUEL PUMP!

Ok, I did EVERYTHING to the POS before I changed the
Fuel pump. As the following.

Computer numbers always first.
Cats, Plugs/Wires/cap/rotar, Fuel filter (changed)
Air filter, Idle control Censer, Vacuum lines,
Throttle body censer, Fuel pressure regulator (Changed)
EGR Valve cleaned, Fuel line cleaned, Top Manifold Cleaned,
im sure there is more I did to it. 3-4 months of checking,
Fixing things and all along I knew what it was.
But everyone was trying to stay away from what it was.

After many hours and money. FUEL PUMP!

Symptoms =
Starts up fine, NEVER ever starting issues!
Cold start - Idles fine, Takes off fine, Driving
and it starts to get less pressure = loss of power.
Then it will act like theres no fuel no power, then
as letting off the gas the idle is fine!

I hope this helps anyone else with the issue of the
Chevy (Tahoe) aka POS on this issue.

Over the last month my 99 5.7 4WD Tahoe has been giving me problems accelerating when I give it a heavy foot. When I hit the gas down it loses acceleration almost like it's being starved of air or gas. When I hit the gas the engines just bogs down, begins to hesitate, and will not accelerate.

It'll drive ok if I'm light on the pedal; and the engine feels smoother than ever.

I already replaced the mass airflow sens, plugs and cables, egr valve, distributor, and air sensor, my fuel pump is about 4 yrs old and my fuel filter is 5 months old.

I get all this but my check engine light does not come on. Only my service engine soon light turns on