04 Blazer runs great till it warms up then dies

[Olewvboy]

2004 Blazer 4.3 engine. This vehicle starts and runs great until it gets warms and you let it set for 5 minutes idling. Then when you give it some gas it sputters. I have found if you move it back and forth when it is sputtering then the issue will clear up until it idles for 5 minutes again.
Vehicle idles fine when it is cold but once it warms up the issue occurs.

[Olewvboy]

Also, I have changed all 3 02 sensors, Catylitic converter, vacuum box behind drivers side rear wheel, MAF sensor.
Question: is there a vacuum hose that goes down to the transmission? It is throwing a pending code of 131 and 151 low 02 sensor reading. but its not bad enough to turn the check engine light on.

[Tech II]

Both codes represent a lean condition in both banks.....

Could be a bad MAF.......a vac leak affecting both banks......low fuel pressure.....make sure the snorkel to the throttle body is tight, with no leaks after the MAF....

[Olewvboy]

Thanks for the reply, Still showing P0171 and P0174 codes. I cleaned the distributor and the P0300 code went away. I have changed the MAF sensor, changed all 3 02 sensors, changed the spider under the plenum cover, changed egr valve, checked all hoses rubber etc that is after the MAF....no holes or dry rot, changed the idle air control, air filter is new, fuel pressure test is at 60+ holds to 55 when you cut the pump off.
The only thing that I have not changed is the throttle poition sensor.
Below is info from the scan tool does anything look out of line?

fuelsys1 closed
load_pct 3.1
ect 194
shrtft1 10.2
longft1 25.0
shrtft2 1.6
longft2 25.0
map 5.1
rpm 618
vss 0
sparkadv 18.0
iat 82
maf .01
tp 0.0
02b1s1 .035
02b1s2 .210
02b2s1 .050

Any help would be great, this has me stumped.

[Olewvboy]

Ok, Changed the fuel filter it was dirty, I also performed a smoke test on the intake it was good. I am still getting P0171 and P0174 as pending codes. I have noticed that I leave it in drive and set the E=brake the voltage on the 02 sensors will continue to operate fine and the engine takes fuel as it should, but when I put it in park and let it idle, after about two minutes the bottom drops out of the voltage on the 02 sensors then it will not take fuel and begins to sputter and cut out.

Has aanyone else run into this issue?

[j cAT]

Originally Posted by Olewvboy

Ok, Changed the fuel filter it was dirty, I also performed a smoke test on the intake it was good. I am still getting P0171 and P0174 as pending codes. I have noticed that I leave it in drive and set the E=brake the voltage on the 02 sensors will continue to operate fine and the engine takes fuel as it should, but when I put it in park and let it idle, after about two minutes the bottom drops out of the voltage on the 02 sensors then it will not take fuel and begins to sputter and cut out.

Has anyone else run into this issue?

what is the fuel pressure when this stalls/O2 sensor voltage drops down low ?

with the testing sounds like fuel pump problem. may not be the pump but the wiring/relay/ground.. if pressure drops then check for the voltage at pump .if the voltage is good ground at pump good then the pump maybe defective and when it gets hot looses its torque to keep the pressure up.