er 1 misfire already changed plugs and other coils

Question

I have a 2002 GMC Envoy 140k that already has codes P0301, B0790 Transfer case neutral range, control circuit short to battery & U1000 Class 2 Data Link Malfunction.
I have replaced all coils and plugs and vehicle continues to display hard run while from 1st to second gear and check service engine soon light is still on after codes cleared.
I  recently had my battery changed and I do have a short or constant draw coming from the rear end of my SUV. I know they are 2 separate circuits but just more info.
Thank
Jessica