I replaced spark plugs, ran fine had a little miss, got worse after 150 or more miles, check engine light came on, had it scanned had p316 code start up emissions. put fuel filter and chemtool b12 in tank ran fine for 60 miles know it is missing ,surgeing should I replace filter again? I listened to fuel injectors they all sound same?

 

What did the removed plugs look like, was one much different in color from the others?
There are certain checks that the PCM does on start-up .

 

yes they had been in along time, I just got the truck, already replaced coils on 5-6 the plugs were in bad shape