2009 sti. Car was running rough before I changed out the timing belt. I also replaced air pump valve under the intake. The plugs have never been changed and it at 90000. So I figured it was just bad plugs and began my tear down and change them in the process. Well I put it all back together and still runs like ****. Checked fault code. Misfire cylinder 1. So I swapped coil 3 and 1 then reset computer. Check engine light back on. Check code. Misfire cylinder one. F@&k. Can being off a one tooth cause a misfire on just on cylinder? I’m thinking not. But I really don’t know. I’m going to do a compression test after it’s cooled off. But don’t want to start getting into injectors if it could possibly be that I’m off a tooth. Like I said was missing before I did this job, but I can’t remember if it’s running the same or worse.