hey guys about 6 months ago i swapped the heads on my 2000 alt 3.0 due to worn/leaking valves, it Ran great up until about two weeks ago and it started misfiring in cylinder 1 (p0301)

i have swapped wires, plugs, coil pack, and fuel injectors. I honestly don't know what else to check and i need help. misfire is in cylinder 1 and it gets a popping/backfiring noise which seems to be going into the intake manifold.

any help would be greatly appreciated!

Might run a compression check, could be something wrong with the intake valve or seat, could be a valve spring or lifter gone bad, or a lobe off the cam.

Ok, I’ll run a compression test again and then I’ll pull the valve cover off and take a look at that. I’ll post what happens

Check your spark plug wires. I know you said you replaced them, the same thing happened to me due to a bad wire. You can check resistance in the wires and if any of them are spilt anywhere.

Also check to make sure all injectors are firing and are working well. Do this by putting a long handled screwdriver against your ear and the other end against the engine near to the injector so you can hear it. If they all sound the same then you can start trying the more difficult diagnostics.

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