So I've had the check engine light on now for about 3 weeks. I took it to Autozone and they said it came back as a misfire on all 4 cylinders. The code related to either vacuum or something else I can't remember. I ordered new NGK's thinking this would fix it, which it helped with a little bit, the car doesn't shake on cold start up like it did before but the check engine light is still on.

The only modifications I have on the car are Alta intake and catch can, but I've had them installed well over a year now with no problems. Any advice on this issue. I don't notice any issues in power that would hint to a vacuum leak. Could it be carbon or is there something else that I'm missing? Thanks.