Honestly so confused on what’s going on. I’ll try to provide a short briefing of the situation.

Around 2 days ago I went to a drive thru, sat for a decent amount of time in drive and about 15 minutes later, my car started overheating and quickly got very hot (noticed overheating close to h) and quickly shut my car and left my car to later retrieve as I couldn’t afford to tow it. Later found barely any coolant within the reservoir, noticed no external leaks. I filled the car up and the car didn’t overheat. The CEL began flashing indicating a misfire. I later replaced the old, worn out plugs with OEM NGK plugs, and replaced an old, broken coil pack. After doing so the car ran very rough on startup, backfiring and misfiring, this time occurring as a multiple misfire code, instead of the original code being a misfire on cyl 6 only. What could this be? All plugs are new and coils are in good shape. Starting to think this could be a internal issue.

(Worth noting till this day I’ve spotted zero coolant leaks, but the coolant somehow leaks out obviously because the level is still low. Also worth noting the car had a cyl 6 misfire when I first bought it but was quickly fixed with a new plug and coil pack, that event was about 3 months ago, oil change has been done and coolant was supposedly topped off at the shop so it’s confusing the engine would have these types of problems even after basic maintenance)

Thank you to those that can help, 2008 G35 Sedan

 

Are you sure you didn't get the coil pack wires mixed up, it's easy to do.

As for the coolant issue, pressure test the system, you're probably losing coolant as steam due to a small leak in the system.

 

I’m not sure I’ll check later today for the coil pack wires.

The last time I ran the car before since this incident I filled the reservoir to the top and let it run for about 10 minutes. I checked yesterday and the reservoir is nearly under halfway. There’s no leaks on the ground so i’m not sure where it would be leaking at, it doesn’t run like it has a blown head gasket.

 

A tiny leak will just come out as steam, not actually dripping liquid. Or it could be dripping onto something hot like the headers.