1999 GMC Sierra Need help with GMC suburban acceleration pr

1999 GMC SIERRA
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RNJSRANCH
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Engine Performance problem
1999 GMC Sierra V8 Four Wheel Drive Automatic 135k miles
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I have replaced air filter,all 4 o2 sensors ,TPS, fuel filter is good replaced fuel pump 6wks ago and CAT's are both fine. Starts fine, after driving 5-10 minutes or incline when i accelerate it sputters and backfires which sounds like it is coming from passenger side under hood loose power .Then turn engine off restart and runs just fine for again another 5-10 minutes?? I keep getting the P0171,P0174,P0131 codes have redone codes several times at idle and while driving? If anyone has any suggestions besides taking to a shop i am all ears here?
Apr 30, 2008 at 2:04 PM
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BLACKOP555
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Check your MAF sensor, ignition timing and try fresh gas with higher octane first.

also check for vaccum leaks they can cause your problem also.

you ever have the ignition system checked out?
Apr 30, 2008 at 4:27 PM
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RNJSRANCH
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how do i check the maf
Apr 30, 2008 at 4:45 PM
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BLACKOP555
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if the wires on it are full of dirt just clean it with qd contact cleaner.
Apr 30, 2008 at 5:21 PM
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RNJSRANCH
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i clean the maf i changed the fuel filter the old was hard to blow threw could the maf still be bad the truck will idle fine but when you put your foot in the gas the truck will back fire and sputter turn the truck off the problem is gone for a little bit then same problem is back
Apr 30, 2008 at 5:24 PM
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BLACKOP555
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it may, and it may not. depends on the severity but i wouldnt go replace it yet, id have a shop test it first.

could be ignition system related, check timing, dont know about plugs, coil, plug wires, ignition module since it doesnt have to cool down before restarting and running good.

also check for vaccum leaks which will probably cause your codes, especially after the MAF sensor.
Apr 30, 2008 at 9:19 PM
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RNJSRANCH
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sorry to keep bothering you but one more question i will be changing the cap rotor and plugs and wires could a timming chain cause this thanks for all your help
Apr 30, 2008 at 10:24 PM
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BLACKOP555
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it might be the timing chain, but turning it on and off shouldnt make it run right

be sure to put the new wires on the distributor cap one at a time! not to mix up the firing order.
May 1, 2008 at 7:06 AM
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RNJSRANCH
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i found the problem it was a fuel pump i want to thank you guys for all your help keep helping people this is great site
May 3, 2008 at 10:35 PM
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BLACKOP555
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I want to thank you for your donation and posting the solution of your problem so others can learn from it!

we will continue to help people as long as possible.
May 4, 2008 at 8:55 AM