Question

how should the punctuation in this sentence be changed, if at all? i already had a sleeping bag, tent, and flashlight, i still needed a raincoat.

Answer 1

I already had a sleeping bag, tent and flashlight. I still needed a raincoat.
The comma before "and" needs to be removed as "tent and flashlight" is not and independent clause, it has to be linked to the rest by the coordinating conjunction. Last sentence is a new element so I would put a full stop before.

Answer 2

I already had a sleeping bag, tent, and flashlight. I still needed a raincoat.