I vote hallucination, simply because you've been reading up on it to try and fill holes, and you seem to be approaching it like a game.

If was real, I don't think you would need to look it, because you would want to avoid it and not think about it.

I have zero experience with hallucinations per se, and 100% reality,
but paranoia, obsessive, mind connecting dots which aren't there, making more and more exceptions to things to fit other parts, such as, the way you see to add more detail but none the clearer.

I have no clue about age, gender, intelligence, or any disorders you may or may not have, but either way, curiosity is good, unealthy curiousity is bad.

I've been with a friend, who at the time was on something, and seen a car park outside the park fence, rear lights still on, he froze, done a mini flip out and run in the opposite direction, Ijsut stared looking at the car squinting, then realised I probably should move to, even though I have no clue whether my mate was tripping, or he had angered someone adn they were out to get him, being seen with him moments before, if it was someone he would run from like that, I probably would bet they wouldnt give a damn that i'm nothing to do with whatever if any thing going on.

Why tell you that? Well, because I was able to be rational even though uncertaintly and inner conflict was there and I made a decision, no doubt in my mind, it was someone he had upset.

You on the other hand, i'm probably closer than further away in saying, you're probably not an ex convict, 5'11'' male who could defend themselve against one or more attackers.

So either you have zero sense of danger or you're delusional
There could be many reasons for zero sense or low sense of danger, which won't list here, but given what i've said above, I gotta stick with delusional. Paranoid delusion maybe.

I too have pretty good memory and remember many things from far away and things others miss, I don't run with the thought though when it's deja vu. It doesn't mean anything TYPICALLY, lol.

Can't remember where read, but it's 3 times before you should start worrying.
Once. Twice coincidence, Three times? :O

Be interesting to see if you could create a map of patterns you could figure out from what yo u see, whether actually is real or not.

I could do it, actually do it all the time, and I don't question my grip on reality (well ok once, that was completly different and I stand by my initial thoughts xD Ahem)

Not sure why i;m on this Q so long, maybe I find it interesting.
Maybe I like mysteries, idk, think about what i've said above though and see what fits and what don't.

Why you watching a car/two guys any way? Think maybe you're in denial about being the stalker? :P

Ofc though there ARE some people who like to mess with peoples minds like this.
I reserve that skill for War, myself xD

Whatever it turns out to be, have fun but be safe.
Make sure to look both ways before crossing the road as well, i've been nearly run over while thinking a little too much. xD