So I am posting this for a buddy of mine, He has a 2003 G35 with a DE VQ35. He recently lowered it, however I don’t believe that has caused any problems, however I don’t even know. Before it died the RPM gauge was bouncing from 1k to 0 and be shut it off after a few seconds of that. He would try starting it and it would struggle and when it did start it would drop to around 100 rpm’s. He has replaced spark plugs, camshaft sensors, Fuel pump, checked ignition coils for spark, cleaned throttle body, crankshaft angle sensor and mass airflow sensor. I’ll have a video below with an example. Anyone have any idea? He’s kinda having a hard time with it

 

If you scan the car, what error codes does it give? It's unlikely there are no codes.
But, other questions or things to check

1 - If you unplug the intake air sensor (near the air cleaner), then start the car, does it behave differently?
2 - Are you sure the battery is good, that's sounds like a possible weak battery
3 - Are you sure all the coils are ok?
4 - When replacing the plugs, is it possible the wires were plugged back in correctly. It's not hard to reverse and accidently switch so the wrong coil is plugged in
5 - Do you have a way to check fuel pressure is good (since you replaced the fuel pump).

Why were so many things replaced? For example, the fuel pump, was it exhibiting low pressure? Or was this just a guess and replace?

 

He checked codes before even anything else, that’s what led to changing all the other parts, He checked the mass airflow sensor already and made sure the coils were correct already. We came up with the idea he could be pinching a fuel line due to him lowering the car somehow so we will be checking into that tmrw afternoon, yeah I noticed the battery after he sent me that video and told him about it and he agrees it needs to be changed. I really think it has to be his fuel lines of some sort, I doubt it’s anything else besides maybe injectors, but I don’t know.

 

Check fuel pressure, That will also give a clue. That would be odd that a fuel line got pinch, but you are right anything is possible.

 

You can see the tach move so it's likely not the crank sensor, it's getting spark and fuel because you can hear the engine ALMOST catch so it's probably not those either.

What's up with that fuel gauge bouncing all over the place?

Are you sure it's not just out of gas? That's exactly what it sounds like, pull the pump and look in the tank to visually verify there's gas, you can't just go off the gas gauge which is HIGHLY notorious for failing.