Okay, neither one will cause the misfire.
It could be a vacuum leak as well. You can have the engine smoke tested to look for a leak. It may be the intake manifold. Remove the oil fill cap with the engine running. Put your hand over the oil fill and see if you feel the vacuum. If you do, it may be the intake gaskets.
Beyond that, it could be mechanical. The valve covers and inspect the operation of the valves to be sure they are moving correctly.
Friday, September 28th, 2018 AT 3:32 AM