2003 Chevy Silverado PO171, PO300 Questions

2003 CHEVROLET SILVERADO
71,000 MILES • V8 • 2WD • AUTOMATIC
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PRIDDLE1
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Hello, looking for some help / advice for my 03 Silverado

About a month ago, my 03 started getting a rough idle when sitting at a stop light,( SES on)

Took it to a GM dealer, they checked the codes, It had PO131, PO171, PO174, PO300, P1133, They said I needed intake gaskets, and Bank1Sensor1 O2 sensor.

I replaced the intake gaskets with a FelPro set, Replaced the Bank1 Sensor1 O2, Cleaned MAF, changed fuel filter.

Still no good, I am still getting PO171, PO300, and now the P1133 came back. I have cleared codes several times, The PO171 pending comes back within seconds, and after a few minutes the PO300.

Still running rough, Leaves black soot under the tailpipes, fuel mileage dropping .

I have tried looking for bad vacum hoses, they all seem ok, Tried spraying carb cleaner around new intake gaskets, Throttle body o-ring, Intake pipes,and all vacuum hoses, Nothing.

Fuel pressure is 54 with Key on
48-49 at Idle
48-49 at 3000 rpm
58 If I snap the throttle hard.

Codes from cheapy code reader :

PO171, PO300, P1133
PO171 pd, PO300 pd

Monitors 3 inc. Catlyst, Evap, O2 sensor

4 Ready. Misfire, Fuel, Comp, O2 HTR

Got a vacuum gauge today.

Connected to the PCV port I am getting a steady 17 in, with only a Vary, vary slight fluctuation, maybe 1/2 in, or so.

With the gauge connected to the PCV port, engine runs smooth, at a normal idle. When I reconnect the PCV valve the rough idle returns.

Any ideas would be appreciated

Thanks

I can donate more money tomorrow, Need to put money in the bank, Right now there is only $ 6.00 in there.
Feb 15, 2010 at 7:29 PM
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