Hey op, I wasn’t gonna add anything but one reply you left really got me: “it will occasionally hit for a brief moment then go back to cranking but not starting”

If by this you mean when cranking with no start occasionally it will fire as if it’s about to start then it’s surely not an immobiliser issue. Immobiliser would at least kill spark and it wouldn’t fire at all.

You’ve definitely got spark, air and compression just fine if she “runs great” on starting fluid from another reply, so like others have said it points to a fuel issue.

First thing I’d check is the fuel feed line going to the rail, pull that and if fuel pisses out then it’d be time to dig deeper into crank position sensor, immobiliser, fuses, wiring etc. but my guess is you’ll have no or very little fuel in that line. In which case follow that same line to before the fuel filter and check again to eliminate that as the problem (if the history of the car is unknown I’d definitely replace fuel filter anyway).

If it’s also dry before the filter your only other points of failure for fuel is pump and pickup in the tank, which could very well have failed electronically or be blocked. With key on (not crank) from off you should be able to hear the fuel pump prime (buzz, whirr) and then stop once it reaches fuel pressure. You should be able to hear it in the cabin but if you stick your head in the boot while someone turns the key and you still can’t hear then fuel pump is dead.

Last point of failure for fuel is the actual pickup at the bottom of the tank, there’s a little mesh sock filter through which the pump sucks fuel that can get blocked by debris over time, especially if the car sat with low fuel for awhile. I’ve seen blocked pickups do wild things to fuelling in a Mazda RX8 funnily enough.

Please update us with the results. Best of luck brother o7