i think this piece, at its core, a weird or eerie idea that could work as a complete whole if you fleshed it out, because it's a fun concept even if i have read similar pieces that showcase liminal or infinite or shifting mundane realities (this includes long or neverending or repetitive highways and highly mundane indoor retail spaces that adjust their boundaries supernaturally to characters inside them) but isn't functioning to its potential right now. i agree with a lot of pallid's critique (the dialogue doesn't land as believable at times, the characters respond to things in unrealistic ways at times, there are still formatting errors, and there are punctuation missteps here and there, meaning that once other, larger issues are sorted, a line-by-line would benefit the piece to nitpick details) and i think the piece would be stronger if these things were addressed, but i think the biggest issue for me with it as it stands is stakes, or more specifically, lack thereof.
the piece begins in media res with the implication that this is a cycle which has repeated an unknown number of times, but the characters do not respond with an appropriate amount of distress in any direction. there are hints of confusion or frustration, but actual people who are driving on a road and pass the same gas station ten or twenty or fifty times wouldn't be so… almost blasé about it as this:
“Look, I don’t really wanna go into there, it freaks me out. Though I don’t know what else I’d do.” Jack trailed off to himself, still holding the phone to his ear. "Sure, I can get something. What do you want?"
similarly, clearly supernatural things happen to the interior of the gas station, and we get this:
“The other two walls are gone now, I swear to god!” The tiny little gas station had expanded; the tiled floor and rows of shelves repeating until they fell out of view. Jack sighed. “This sucks.”
it totally deflates the horror or spookiness of it with how understated jack's responses tend to be. we might get one or two lines where he is hitting us with stuff in exclamation points, but this would be unnerving, confusing, disorienting — almost none of that is really present in the way he reacts. we don't feel that there are any stakes because, if there were, the character would be reacting as if it mattered, what he was experiencing.
and i think this speaks to a bit of a broader thing too: what differentiates these two characters? what are their personality traits? they feel like props more than characters to me much of the time; they're often stiff and "teenager-generic." this would also help raise the stakes of the piece: if you give us distinct characters with personality we are way more likely to be invested in what's going on with those characters throughout the course of the piece.
i think we also lose a lot of believability in the section where, bounded on either side by dialogue, jack walks for tens of miles. ten miles is a three-hour hike; tens of miles is an all-day affair, and the dialogue completely drops during this section to describe the surroundings. is jack just silent for twelve hours? is sam just waiting on the other end? it wouldn't be an issue really — i could chalk it up to "general weirdness" — if the dialogue didn't drop and resume so suddenly before and after.
the ending, because the stakes have not been established very strongly (i do not feel invested in the characters enough through the dialogue, and the horror or eerie vibes are not evocative enough to carry the piece), does not land particularly well for me either. i struggle a bit to determine what exactly the ending is meant to signify, partly due to the pacing and the POV shift, i think, but also because there is a bit of whiplash between the abrupt decision to suicidally drive the car into the gas station and the suddenly-frantic sam who then reaches jack on the phone after all. was sam hallucinating? was sam's anxiety driving the narrative the whole time? was jack hallucinating? it doesn't feel clear to me.
all of this said, do not despair or give up! i don't believe this is something you need to throw out and start over, or something you cannot work with. i do think it needs some polish and attention to your goals with where the piece begins and ends and how it gets there to really shine, but i also believe that you can do it. you have a lot of fundamental skills, a solid idea, and the storyteller's spirit, so keep it up!
just my two cents.