When my engine warms up it starts to slightly miss/stumble and knock. I traced it to #5 cylinder exhaust cam side. It is and unsteady knock and goes away on 1800rpm and up. There is no knock or miss through out the entire rpm range. Only when I come an idle, the engine rocks/misses and knocks and only seems to be on #5 cylinder(exhaust side). I used a stethoscope to confirm this.

I've swapped coils and injectors around and still have the same issue. I also swapped igniters and coil harness. Would crappy fuel cause a knock at idle?