Q: Engine misfiring

It is possible that the spark plugs and wires, or even the ignition coil, may require replacement, but the intake manifold is a highly unlikely cause of this trouble code. Any issues related to misfires are usually found in the ignition system, which can be diagnosed through an engine misfire inspection I would recommend having the spark plug on cylinder three pulled out by a mechanic to check its condition, as well as checking the wire that powers it. If these two seem to be faulty, have them replaced as well as all other plugs and wires; this is a periodic maintenance service that is necessary anyway. It is also a good idea to have the ignition coil tested to ensure it is functioning correctly. If not, have the ignition coil replaced.