Ryan, I'm not certain if this affects SRAMs, but an hour ago my (excellent) mechanic told me that the Connex chain I was purchasing requires the master link to be oriented in a particular direction. To be precise, the point found in the center of the cut-out has to be facing the outside of the chain.
You might consider replacing the master link with a conventional link to see if it is the culprit.
If the problem is not associated with the master link, I'd try using a fresh freewheel to confirm that your cogs haven't bedded too much. Wear there can be tricky to spot or measure unless it is very bad indeed.
So far as I am aware, SRAMs compatible with 8 and fewer speeds (the PC-48?) are made to the old SedisSport design and should perform adequately, if not in an exemplary way, in applications like yours.
Good luck, and welcome to the list.
Kris Green
Olympia WA