So I have burnt cylinder 3 exhaust valves twice now. I just fixed that again and replaced the fuel injector on that cylinder only.

While apart I just did a 15% pulley and 1 step colder plugs. These NGK plugs are gapped at 28.

Now I am having a misfire issue on cylinder 1. If I shut the car off, it stops but will come back. Could the gap on these plugs be causing this issue? Could it just be a bad wire or the coil? Can I test the injectors?

Thanks in advance

 

So if im correct , you changed the pulley and plugs and that's wgen the missfire began ?
people will argue this but try your stock range gear plugs . I've had cars that on paper needed a range colder but they always misfired unless I was throwing big boost or nitrous at them.
my car now has a lot more mods than yours and I ran it 6 months and finally checked my plugs and it still had the stock heat range plugs , lol they were even loose but the car ran perfect . want me to send you my old ones for you to try ? I saved them and you can have them mile send them tomorrow . obv you don't owe me for them but if you wanna try them you can because they worked just fine in my car with my mods. So tgen that for sure would eliminate injectors or plugs being bad
is your coil new ? You sa8d changing around the wires didn't make a difference so it's for sure not those.

 

You do a compression test? is the head gasket leaking? My cyl 3 misfires occasionally when not warmed all the way up but it has compression loss in cyl 3 with leak into 2 and 4.

Also thanks @MiniManAdam for the 'might not need a range colder' comment, as I'll be doing similar changes.