Hi, I replaced coil packs, plugs, and plug wires. I still have a random multiple cylinder missfire. I did one 02 sensor. I put intake gaskets on it and both knock sensors and knock sensor harness. The shop I took it to said it's only misfiring on the passenger side. Cylinders 2,4,6, and 8 only with occasionally cylinder 5. He said the psi on my injectors was good and the all my 02 sensors were reading correctly. He said it beats anything he's ever seen and he's not sure why it'd only missfire on the passenger side. I've been dealing with this for a while now. Also the misfiring is Intermittent. It comes and goes. When it does missfire its not like a struggling for fuel missfire, but seems like you took a few plugs out or plug wires off and it's running on less cylinders. When it does this the check engine light goes from a solid on, to a flashing. Drive a few miles and it'll eventually straighten its self out and the light will go from l
flashing back to solid. A few minutes or miles later, it'll go back to running on less cylinders and the light will flash again. O far ive sunk 2k into trying to diagnose and fix this, yet i still have the same 2 problems. Can anyone please help me?!

 

You might have a pcm problem. The pcm provides the ground to fire the coil packs and injectors when running.. The power is supplied through a fuse. Check for burnt wires under your fuse box and when it starts to miss check for ground and power at the coil packs. Same goes for injectors. For injectors you could just plug a noid light in. On another note you could have some damaged cam lobes on the cylinders also cause by weak lifters.