00 Maxima Blinking Check Engine light, and now won't start
 

I have a 2000 Maxima for the past year, a few months ago I started to have some troubles with it, the check engine light started blinking and if there was a subtle metal smell, kinda when you use an angle grinder, I stopped the carr and took it to the shop, they found nothing wrong with it, then it happened again, OBDII returned a P0300 code and nothing more, but when you attempted to accelerate to get into the highway it would hesitate and start revving extremely slow (this was just after the first time the check engine light turned on).
I've already checked the coils and spark plugs and they are working fine, only a little bit of oil in the spark plugs for cylinders 2 and 4 (will replace the gasket this week).
The car has been sitting in my garage for 4 months now only starting it once every week, last month I cleaned the throttle body and after that it would go into safe-mode and not revving over 2000 RPM now, last week the car would not start, the battery is charged and the starter is making an effort, the fuel pump is working at 60 psi, I haven't replaced the MAF yet.

Any suggestions on what could it be?

that smell doesn't sound good
i dont' think i can be much help but i THINK the car will start with the maf unplugged so maybe try that
because i remember getting the wrong year maf and the car wouldn't start but the car did start with it unplugged.
so maybe that might help to see if your maf is the problem.

You are having problems with the ignition coils. The check engine light will flash at the exact moment an ignition coil is misfiring. P0300 says more than one coil is failing, but unfortunately doesn't say specifically which ones.

Now that the engine is not starting, do you have any additional codes? Maybe the crankshaft sensor is bad.

I got the car to start and it is running good however the low fuel light is on even though it is like half-full, I had to replace the wiring in the fuel pump to have it start again. The check engine light is on but no weird noises nor smells, I will get the code reader again so I can narrow down the issues, thanks for all your advice and inputs.

I already checked the codes, it is showing a P0306, the same P0300, and a P0464, I was able to fix the fuel pump but the injector, coil, and spark plug for cylinder 6 are working fine, but still idling rough and getting the same codes, do you have any other ideas on what it might be causing the issues?