Hi guys

I've got a bugeye sti, stock standard. On the highway I gave it a squirt through second and third then cruised. I stopped at the lights and noticed a funny idle. Then further down the road the engine not sounded like it was missing. Then lost power on throttle. I limped it back home. On idle, the engine shakes, fuel smell from exhaust.
I'm guessing a dud coilpack. I've fixed this on other cars. But on my sti, I'm a bit confused. There is No CEL and i plugged in a obd scanner but no fault codes.

Will a dud coil pack throw a fault code?

Fixed.

I cleaned the MAF - no change.

I pulled the lead on coil #3 - no change (which made me suspect bad coil #3)

I pulled the lead on coil #1 - worse idle (which reinforced my preliminary diagnosis)

To confirm, I swapped coils #1 and #3. Problem was that the symptoms did not follow the suspected bad coil #3.

I then checked the passenger side. Immediately I saw the fault - the lead on coil #4 had partially unplugged. Replugged the lead and SCORE. My STi is now purring and boosting as it should.

Interestingly, even after pulling leads from the coil, I ran the obd scanner (with the lead still disconnected). No CEL and no fault codes.