I got the misfire code once in a while and i dont think it is ignition related for several reasons as most everything is replaced and i dont have many of the opti symptoms. My friend mentioned it may be injector/fuel system related. How do i start to diagnose the fuel system? So far, fuel pump was changed 5k miles ago and i ran some seafoam through the tank at the same time . Is there any way to test my fuel pump or find out if any injectors are clogged? If an injector is clogged, what should i do?

I was thinking I am gonna run some techron next fill and then possibly change the filter again. How do i go about diagnosing and cleaning the injectors?