1999 GMC Sierra Truck won't excellerate???

1999 GMC SIERRA
140,000 MILES • V8 • 4WD • AUTOMATIC
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JACKINTEHACHAPI2
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Seems to be a problem with a rebuilt transmisson. When climbing up a grade the truck won't excellerate. Seems to be in some kind of safe mode and will only go around 20 mph. Eng will not rev up past 2000 rpm?????
I replaced the fuel pump, fuel filter, throttle position sensor.
Oct 31, 2008 at 10:53 AM
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MERLIN2021
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How does it rev when it's in neutral? Does it seem to be a plugged converter? Or is the engine smooth and just not moving? Let me know about the revving in neutral.
Oct 31, 2008 at 11:28 AM
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JACKINTEHACHAPI2
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[quote:4fe686151b="merlin2021"]How does it rev when it's in neutral? Does it seem to be a plugged converter? Or is the engine smooth and just not moving? Let me know about the revving in neutral.[/quote:4fe686151b]

It revs but not like it should, also needed to mention this all starts when the transmission fails to shift then the rpm stay's at 2000 rpm and will not accelerate.
I finally got 2 fault codes to read. One code was (p0131) say's 02 Sensor Circuit Low Volts (Bank 1 Sensor 1) The 2nd code (p0300) say's Random/Mulitple Cylinder Misfire Detected. This truck has four 02 sensors. 1 in front of the converter, and 1 in back on both sides (2 converters). Do you know which sensor is the one noted in the fault code. They cost around $90.00 bucks each.
I was also told the mass air sensor may cause this problem? Is this probable.
I am repleacing the spark plugs, MAP sensor, & PVC valve to see if that helps.
If there is an internal electrical problem in the transmission causing not to shift, would there be a fault code reading?
Nov 1, 2008 at 2:07 PM
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MERLIN2021
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Test the 02 sensor, and fuel pressure:
http://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm
Go here and checkout our video.
http://www.2carpros.com/affiliate/uid/merlin2021_1
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Nov 1, 2008 at 2:45 PM