Can try doing a crank shaft variation learn procedure with a bi directional scan tool and see if clears up. Have see a lot of 6.0L that this will take care of it.

Hi Guys,
I am back still with the same issue P0300 code. I have replaced the spark plugs, wires, coils, intake manifold gasket'* and all the fuel trims are good and fuel pressure is also good, truck runs great except for a small vibration after warm up also the CEL comes on and goes away on it'* own doesn't sound like the lifters are making any noise. All the groundings are also cleaned and good

Any help would be much appreciated as always.

Hasib Khan
San Francisco CA

What is the fuel pressure at the fuel pressure test port?

How many miles on it now?

What else has been done to it in the last 780 days?

Sometimes having the PCM flashed will clear these.

Thank you for your response. The pressure when ignition is on goes to 55 psi and drops down to 45 psi pressure when started holds at 55 psi I have 115000 miles on it and just last week I replaced the intake manifold gasket

I forget: Has a compression test been done? If so, could you remind me of the numbers?

I am sorry I don’t have that handy as the last mechanic did it and I don’t think he still has it

If you don't flash the PCM you could waste a lot of time and money.

How do you flash the pcm?

If it was recorded in the repair paperwork, and if the paperwork is printed from a computer, he should still have it. I agree with carfixer007 that a reflash might be in order, but that would probably require paying for dealership time. If you can get the compression test numbers, that could tell us a bunch.