I have a 4.0 engine that was runinggood before the head gasket went. Resurface the head and had the Vales done. Put back together and started to misfire on to cylender. Pulled the coil pack off turn it over and put the spark plugs in, hooked a wire around them and turned the engine over the first and last one didn't fire. Baught a new one and it did the same. So I put in a new cam sensor in it and no Change. No getting any code from the computer or any check engine light.