Not starting

Oh, and I wanted to add, there are no DTC's upon scanning.

Thanks for the info, Kenny.
Okay, I just tested the fuel pressure. The gauge was bouncing around 50PSI while cranking, and when you stop cranking it dropped to 41/42 PSI and held there.
So, I'm guessing fuel pressure isn't the problem.
Now, I tested the fuel injector plugs, but while all four are unplugged, they all have power, and they all show pulse on the negative side while cranking.
I pulled the injectors, applied fuel and pressure to each one individually via a can of carburetor cleaner and hoses to adapt it together. Applied 12v and ground, all 4 sprayed a nice pattern.
Is it possible that everything works individually but not when it's all hooked up together? I read that if one injector shorts then none will fire.
I'm thinking I'm going to pick up a mechanic stethoscope and see if I can hear the injectors pulsing while it's all hooked up and the engine is cranking over.
What do you think?

Another update: I just double checked that the injectors are getting power. They are receiving both while the key is on engine off, and they also get power while cranking.
I also double checked for pulse on the ground side and all four are getting pulse while cranking the engine over.
I then broke out my multimeter and tested each injector for amp draw. All four injectors draw.85 amps with 12v applied.
I do not have a stethoscope to listen to them during cranking though. It's hard to try to use a screwdriver when the engine is not running because it shakes more trying to crank it over.

Anything else I'm missing? Any idea which wire coming from the ECM is the injector pulse driver?

I also want to point out the obvious, yes there is definitely lots of gas in the tank. And it is not old.

Okay. And this is a return-less fuel system, so the fuel pressure regulator is in the tank with the pump. Local parts places don't have it in stock so I'm going to order it online. So, it will be about a week before I get it, I hand and be able to follow up here.

Actually, I'll do a short video of the gauge when I get home later and put it here if I can.

Here's a short video of the gauge.

Okay I just checked. I see no security lights on the dash. And with key in and in the on position I waited a bit and no lights come on either. I read that a green key light will flash after 10 seconds of the key being on I there's an issue.

To check for pulse first I got my multimeter and tested a injector plug for power. The pin on the right gets 12v with key on and continues to get 12v while cranking. The pin on the left is the pulse signal, to test it I took my test light and put the alligator clip on the positive post of the battery and put the probe from the light in the left pin on the plug. When cranking the engine over my test light flashes. I tested all 4 plugs like this. I can do a video if you'd like.

Another note, I'm going out of town tomorrow and will be somewhere I can get a stethoscope, so tomorrow night I'll be able to listen to the injectors while everything is plugged in and see if they are in fact firing or not.

I read in a few different places. Some say all Mitsubishis have immobilizers since 2000. Some places say only evos have them, and some places say some cars have it and some don't. So very mixed results.
I looked under the dash by the obd2 port. I can't see anything that jumps out at me. Unless I remove more panels to look deeper. In the diagram it looks like it's more under the HVAC/fan controls. I can pull those panels tomorrow too to look
But I also looked in the owner's manual and see no mention or an immobilizer or alarm system anywhere in the book.
I did get a stethoscope today, but the wife is not feeling like going out to the garage tonight to assist. So, I'll check that in the morning.

Okay. Big update. I bought this car a few weeks ago in its none running state. The fuel pump wasn't getting power I was told, the owner replaced the fuel pump, not the issue.
Apon some research I replaced the cam and crank sensor. One may have been bad. When I was testing for power, it was just key on engine off. But after more research I found out these cars don't prime first; the pump only runs when the engine is cranking. So, if the other owner wasn't getting power maybe he thought it should prime as well? But if he actually wasn't getting power, one of those sensors likely fixed the issue.
So now, I tested for spark, all 4 sparked fine, but I used a spark tester to check for spark.
I just used my stethoscope; all injectors are firing. I was ready to message here and say what do I do now, must be fuel pressure. But first, I decided just for fun, I'm going to pull the 4 plugs and test them for spark without the tester, just spark plug against ground. First 2 I check were good. Second 2 had bad to no spark. I had 2 old plugs kicking around that fit, they sparked good. Put it all back together, crossed my fingers, wife pushed the clutch and turned the key.
The old girl fired right up.
Why it started when I used the starter fluid before is a mystery. But she's running now!

Going to get four new plugs for it tomorrow.
Thanks so much you guys for helping me out.
My new daily drivers going to be on the road soon. :)

So, you'll probably never believe this. After my last post. Bought four new plugs the day after. Installed them, car fired right up, ran, and sounded great. Let it run and drove it around the yard for almost an hour. It wasn't registered for the road yet at this point. I was waiting to get it running first.
So, three days later, car sat behind the house where I had parked it. I got the car registered at the DMV, got the plate, all good to go.
Day after that I decided I'm going to run it over to my friend's place who has a hoist, so I can get a good look underneath and check the ball joints, wheel bearings, tie rods etc. Just to make sure she's good and safe for the road.
She wouldn't start. After several failed attempts, I pushed it back into my garage, my first thought was to check the plugs, to my surprise, no fire on any cylinders. I checked all 4 plugs, and checked the coils with the spark tester, nothing. I have no injector pulse. And no rpm signal while cranking.
The fuel pump does run while cranking the engine. Swapped out the new camshaft sensor with the old one. No change. Crank takes time to get to. But from earlier testing it seemed the camshaft sensor was the one responsible for the tach signal. But not positive. The cam sensor, I tested the wires. 1 outside has continuity with ground, the other outside wire has 12v with key on, and the middle wire has 5v. If I back probe the middle wire with the sensor plugged in but removed from the motor, it gets 5v and it drops to 0v if I put a wrench next to it. So, I'm thinking the sensor is working. One thing, the cam sensor had oil on it when I pulled it. Is there supposed to be oil inside where the cam sensor goes? Also, while back probing the middle wire, I installed the sensor back. And put a test light on the middle wire, and other end to ground, the test light did not flash while cranking, but I'm not sure thinking about it now if my test light works for 5v or not, I'll have to go check. Are there contacts inside where the cam sensor goes that could have fallen out or something?
And I did recheck the compression, same as before, 210 across the board, so not a timing belt issue.

I cleaned off the sensor, and I tried to blow out the area inside where the sensor goes, there's a lot of oil in there. Should it be dry in there? It still didn't start. Maybe I need to replace a seal in there?