Q: Engine is misfiring - 2001 Nissan Maxima

There are some "interrelationships" between "parts" of the exhaust system and engine misfiring. First of all, if the engine is actively misfiring, this will destroy the catalytic converter which is often the most expensive exhaust system component. Of course, that means that prior to putting in a complete new exhaust system, the engine has to be in proper operating condition because you don’t want to spend money on a new converter (again, a key component of an exhaust system) only to have a misfiring engine promptly destroy the converter.

As far as a bad exhaust system "causing" engine misfiring, generally that does not occur except that, again, with regard to the converter, if it is plugged and restricted (due to the engine having misfired over a period of time), the engine’s operating condition will generally be relatively poor and it may even appear as if the engine is misfiring.

I recommend having a certified mechanic, such as one from YourMechanic, come to your location to inspect the misfiring and determine what has gone wrong with the exhaust system.