since the repair my lights have been dimming very slightly

The lights on the same circuit? Or lights on a different circuit?

i capped those wires off in a junction box

This is the 'dead' side of the circuit right?

and put a new outlet in a junction box on the other side of the break

Ground on the green screw, white on the silver screw, black on the brass?

From your description, it seems like you did things properly. Pictures of what you did may shed more light on the situation (pun not intended).

The lights dimming MAY just be a coincidence and the problem may lie elsewhere.

There are enough variables in what you describe that you may not have dealt with this properly or safely. No insult intended, but based on the questions you are asking, it sounds like you have only modest knowledge of how wiring systems work. I suggest you consult an electrician, who should be able to quickly diagnose whether this was fixed correctly, or poses a fire or shock hazard. It will cost a couple of bucks, but would be worth it for peace of mind.