what makes my 04 gmc sierra run rough,pop through exhaust,and pop a po300 code

Asked by May 14, 2014 at 10:31 PM about the 2004 GMC Sierra 1500 2 Dr STD 4WD Standard Cab LB

Question type: Maintenance & Repair

Po300 popped up and I changed the plugs and wires...reset the code and the next day its
comes back on...took to a shop they said to change plugs and wires and 02 sensor...did
all that with same result...now they tell me I got a bent valve...someone told me to change
the crankshaft positioning sensor which I did and after the truckwouldnt start....so I put
the old one back in and it runs but like shit....please help

1 Answer

Thanks for nothing

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