I'll try to explain this with as much details as possible since I do not have any photos or video. 04'STI, 148k miles stock.
Well, this has happened a few times but has not occurred in a while so I assumed it was fixed. Yesterday after turning off the car and heading to BK, when I got my order I left. When I turned on the car it began to shake and then I noticed smoke coming from the right side of the engine bay. I immediately turned off the car and back on again, same thing. So I decided to wait a while and then it went back to normal, I still drove home very carefully.
** This happens basically within the same time frame 5min; turn car off, leave for a few minutes, turn back on -- then noticeable shaking starts with smoke coming from engine bay.**
I just really need to know what this is before it gets worse, also can it be that my brother accidentally put 89 octane gas instead of 93 a few weeks ago (I quickly changed the gas, since I noticed knocking noise meaning he put wrong gas, which thankfully the noise is slowly reducing).
EDIT -- I found a video of how my idle was everytime this happens, only thing is the car in the video is a WRX. I was looking for another one but with a STI, no success.
Thanks everyone for the help