PLEASE help with this NIGHTMARE

2015 Chrysler 300 V6. So this started out as having a misfire on cylinder 2. I went ahead and changed plugs, coils and injectors as it was about 170k anyways. I also changed out MAF sensor. Still having an issue so I took it into dealership to have it diagnosed. They called me 3 hours later and had hydro-locked my motor and took no responsibility for it. I then bought a new crate motor and put it in. Weird as it is, it still had the same problem. Keep in mind that it was a long block with new heads (so not a head problem). It had a new PCM and both wiring harness replaced and yes still has an issue at number 2. Everything has been checked and functioning as it should with the exception of running right. Also, another weird thing is that if you shut off another cylinder the whole motor will cut off. PLEASE help, I have about 8-10k wrapped in this and still cannot use it.