I just bought this car and it’s beautiful. 116k miles, really well-maintained. The other night, it didn’t start. Tried several times, all the lights came on inside, but it wasn’t trying to turn over at all. Tried to jump it even tho I was convinced it had nothing to do with the battery, still nothing. Tried a few more times. Eventually, she started. Let her run a while. Shut her off, turned the ignition and she started right up super smooth. Did that a few more times. The next day, she sounded rough, like she didn’t want to start but did turn over and start. Was like this all day yesterday, every time I turned the key she sounded like she didn’t want to start (but always did). Then, this morning, she started up smooth as ever. Shut her off and turned her back on just to see, still super smooth. Drove her to work, parked, decided to pull up a little bit and when I went to start her back up, once again, sounded like she was struggling to start.
the starter, fuel pump, distributor cap, all new. The inconsistency of the issue is super confusing to me. I’m thinking it must be some kind of electrical wire that’s loose or corroded? Has anyone ever had a similar problem? Can anyone point me in the direction they’d start in?

some photos for attention: