And car wise a vacuum leak usually leads to a high idle if im not mistaken. But right now it seems to be struggling to idle at all and when giving throttle input it stutters and acts like it wants to die then all of a sudden catches up and revs to life.
Yes, a simple and pure atmospheric leak into the intake system will bump up idle.
I mean a leak that does not screw up a sensor or some kind of actuator, like an intake manifold gasket leak.
Past that, let's look at the engine instability you have described.
Then consider there are there elements involved, air delivery, fuel delivery, and ignition delivery.
It doesn't sound like ignition to me.
If there are no leaks in the entire vacuum lines network, then there there is no uncontrolled additional air delivery.
That leaves fuel delivery, plus what you describe also sounds as though it could be fuel delivery related.
BUT if it is fuel delivery related to physical contaminants getting to the injectors, I am extremely doubtful that any cleaner will help.
The injectors have extremely small discharge openings, so "chunks" can't pass and/or will get wedged at a seat.
Chunks will not be soluble in the cleaner, and be too big to pass on the basis of detergency.
Also, the FPR stabilizes the fuel pressure, so if the FPR is getting erratic or inadequate vacuum, it will screw up the stability of the fuel delivery to the injectors.
Electrical is not at all my forte, but I see that the FSM gives resistance, ground fault check and voltage supply checks to be done.
The original FPR worked.
The replacement FPR worked well.
This suggests that the FPRs in isolation are not the problem.
Therefore, what energizes the FPR might be involved, as in vacuum.
You suspect fuel tank contaminants may have gotten into the fuel system.
Perhaps the injection ports and/or seats are contaminated.
All 4 injectors are displaying a code, and the same code.
This would suggest a common electrical issue before the injectors.
OR maybe the ECU is smart enough to sense that the injectors can't full cycle because of physical contaminants preventing so.
Hopefully the above is of at least some help to you.
All in all, very frustrating for what is supposed to be an easy task of putting on a new FPR.
It will get figured out though, right?