2006 SS 2.4 stick shift with 176k on it

Whenever I back up the engine misfires when I let the clutch all the way out. I can slip it some and it won't miss but when the clutch is all the way out it starts to buck and miss. Drives forward just fine. It's not from lugging it in reverse either, I can take off in second and lug it and it takes off just fine. No check engine light but when I plug my scan tool in it gives a pending P0300 random misfire.

Spark plugs are 20k miles old. It's been doing this for a couple months now, I figured eventually it would get worse and I would be able to isolate a cylinder and troubleshoot from there but so far it's only a problem in reverse.

Any thoughts?