Multiple misfires


Asked by Apr 08, 2014 at 05:41 PM about the 2002 GMC Sierra 1500 SLE 4WD Extended Cab SB

Question type: Maintenance & Repair

truck will not go over 30mph when it does code comes up for multiple misfires and you
are unable to throttle down anymore. have checked everything for air leak. nothing comes
up. just replaces header gasket and exhaust manifold gaskets. code p300 keeps coming
up have also replaced fuel filter. believe it might be the fuel pump. any answers?

3 Answers


Maybe check your spark plugs too.


I have changed all spark plugs and wires.


Maybe your computer needs to be remapped.

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