FWIW...a number of years ago I had a living room circuit that was intermittent, not all the time but just every now & then. At some point I decided to find out what was going on so I started at the service panel and started by replacing the breaker. Everything seemed fine until it wasn't. [tongue]
This issue took a long while to track down but long story short, it turned out to be a back stabbed electrical outlet that was causing the intermittent connection. I just happened to see a couple of very small burn marks on the rear of the receptacle. I was lucky. [smile] After that education, I rewired the receptacles using the screw connectors.