My girlfriend's Dakota didn't have the oil changed for 5k miles (yes I know that is bad) and it was running pretty low on oil. It got cold out here (about 15 deg F) and the truck started making lifter noises until Wednesday it was making a loud clack sound every few seconds but not consistently. It threw an error codes P300 and P304.

I changed the oil and cleared the codes, let it warm up hoping that it was lifter related and after running for a minute or so, it started making the sound again so I turned it off. P304 is a misfire but this does NOT seem like a misfire symptom and I can't imagine it would knock that hard at idle. Any thoughts as to what this can be? Could a bad injector or coil cause a clacking at idle?