Rep Power: 0

Hello, I recently bought a 2002 Civic Si. The seller told me it had a misfire and didn't want to deal with it. No problem, I figured I'll take on the project, price was right in my opinion. So first thing is first, he said he did a motor swap to the JDM version of the k20a3 so pretty much the same engine. Car was definitely not taken care of but anyhoot here's where I'm at so far and hopefully I can get pointed into the right direction. Btw they removed the CAT and just put a straight pipe with the o2 sensors attached. I got the car and it had a very noticeable misfire coming from cylinder #2. With codes p0302 p1167 p1166 which the first one is for the misfire on cylinder #2 and the other 2 it look o2 sensor#1/o2 heater codes I think. Well I checked the coils and swapped them to a different cylinder and still had the same misfire on #2. I ended up getting the correct laser iridium spark plugs and made sure to not gap them and still had the misfire on #2. Also right before I added the new plugs is was running well and then all of a sudden it went back to misfiring. So pretty much at this point its running well at random times. So now with the plugs I start digging a little deeper and fine out that by deleting the check engine light, it would start idling well with no misfire for a little bit. So now somehow the car starts running fine but what I kept doing was delete the check engine light every time it came on. When I reset the check engine light I would drive the car pretty hard and the Check engine light would stay off until I would come to stop to idle and if I didn't delete the code in time it would go back to misfiring. So right now I'm leaning towards fuel injectors but I don't have any codes pertaining to the fuel injector unless the ones coming up are due to bad fuel injectors. So as of now I went and got some Lucas injector cleaner drove it on the highway pretty hard without any issues(btw it seems to work better under acceleration in general when it's running without a misfire). As soon as i got off the highway and stopped it started to misfire again which I finally parked and cleared but this time it added codes p0300(random misfire) p0304(misfire #4) to the mix while also taking a couple tries of deleting the light to get it to idle normally with no misfire. So right now I was able to delete the codes and it's idling well. But why does it start running normal after deleting the codes.