2003 2500 hd po300 code

[simmons2]

My 2003 2500 hd with 6.0 is showing po300 code when first cranked.Truck runs rough no power then like flip switch and runs fine.Installed new fuel pump and filter and still runs bad when cranked.

[ujtruck]

 

[ATMINF]

How many miles on the plugs and wires?

[Chris]

My p0300 came doen to tuning and then plugs and wires

 

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[simmons2]

Have not changed plugs and wires in couple years

[ATMINF]

I would say check them out and see if they are the issue. The best trick I have used is to have it running at night, and since its dark, you can see if the spark is misfiring. This way you can see which plug is going bad etc... Good luck.