what can cause a misfire reading on my car after i have changed the head gasket?

What is your question?

everything is back in place the car starts but it idles hard and acts like it is not getting power and then it will die when i stop. I have hooked it up to scanner and it says that i have p0300,p0301,p0302, p0303,p0304,p0314. what should i look at?