I bought a 188K 2011 Ranger which is the 5 speed automatic and 2x4. It's bone stock.
I've been having an issue where it will randomly die on me, whether I am sitting idling, putting it in gear, driving 50 mph on the highway or accelerating from a light.

So far I have replaced the fuel filer and it did not seem clogged, checked all the fuses and relays (even changed some around with same values), and also the inertia switch.
The battery is also good at 12.36V and over 14V when running.
I'm currently driving with a check engine light due to the catalytic converter slowly rattling itself to pieces. I used autozone to pull codes but only see the catalytic converter not working.
I was stranded on the highway, but after I hitched a ride to work and back 7 hours later, it starts back up.
I took the backroads home and it would die on me 5-6 times.

I can tell when it's about to die, because the blinkers will go quickly, or if I am reversing the reverse light will go out.
When I was troubleshooting it at home, I would hear the fuel pump prime fine, then it would die. Shortly after the pump would sound weak, or there were no sound at all.
After it has been sitting for a few days, it starts fine and runs great.

I suspect the cam position sensor or maybe the catalytic converters are messing with the O2 sensors...IDK...Help? What am I missing?
The engine runs fine but has some oil leaks underneath (minor stuff that doesn't leave any drips on the ground).

When it dies while driving, I am able to throw it in neutral and start it back up.

 

Welcome to the forum

The fuel pump only runs for 2 seconds with key on, doesn't run again unless you cycle key off and on again, or engine is started, gets above 400RPM, then it comes on full time

If it was a "sensor" issue you would get codes for that, if computer was on

Watch the CEL(check engine light) when engine stalls, with key still on the CEL should come back on, or in your case stay on because of the current codes, if CEL is off after the stall that means Computer is powered OFF, so electrical issue and no codes since computer is OFF

There are no Cat converter codes?
What were the exact codes?

Yes, plugged exhaust will shut down an engine and cause a no start, i.e. the potato/banana up the tailpipe "trick"
If Cat, or muffler, has loose pieces inside they WILL shift around because of exhaust flow, so can block and then unblock exhaust flow

 

The code that showed was P0420: Catalytic System Efficiency.
"The fuel pump only runs for 2 seconds with key on, doesn't run again unless you cycle key off and on again, or engine is started, gets above 400RPM, then it comes on full time"
The fuel pump has had moments where it doesn't give the full 2 seconds, but less that a second and the sound is lower. Gives a "woop" sounds instead of a "weeeeee", or nothing at all.
Right now it's working again, only stalled twice on my way to work.
I already bought a replacement catalytic converter, but I managed to strip one of the bolts while trying to take off the old, so I might have to let "the experts" deal with it.

The check engine light stays on when it dies, and the red battery light comes on.
It's also shown as low oil pressure before I start the engine, but goes away when it runs.

 

P0420 would indicate older O2 sensor(they only last 12 years) or a failing Cat Converter

But no reason for engine to stall unless exhaust was being restricted momentarily

Computer monitors Fuel pumps 12volt power when computer activates the Fuel Pump relay, so it would set a code if fuel pump relay was not sending 12volts to the pump
There is no fuel pressure sensor so computer can't monitor if fuel pump itself is actually working when it gets the 12volts, or if it stays working while driving

Could be a poor wiring connection on the top of gas tank causing low or no voltage to fuel pump intermittently, or fuel pump itself

 

I'm taking off the bed with a friend to get access to the fuel pump this Sunday.
Question is, should I:
1 Troubleshoot for wires/connections
2 Replace the fuel pump motor
3 Replace the entire fuel pump assembly?
That's $30 for the pump or some stores sell the pump assembly for $250-$300. I've seen them as low as $60 on Amazon but I don't completely trust the quality.

 

From 1998 thru 2011 Ranger had a 3 part fuel pump assembly
The pump
The Sender/float
The FPR(fuel pressure regulator)

Both the pump and the FPR need to work in unison or there are issues
So replacing the whole assembly, if this is what you think the problem is, is best

As to the brand, that will be related to how much trouble you think it is to lift/move the bed to gain access to the top of the tank
Cheaper brands have long warranties, sometimes 2 years, this means these were never tested, you are the quality control, and either they pass or you return it for another one

Motorcraft(Ford) brand has 90-day warranty, these are tested, but testing each assembly is expensive, it's labor

One pump is not automatically better because it costs more, the "better", as far as fuel pumps, is will I have to go back in to replace it under warranty
So if its not a big deal to you to swap out the assembly then save the money on 3rd party brands, your hard earned money, well worth it, just SAVE the receipt for warranty if needed

 

So after giving up, I took it to a mechanic. Had to replace the catalytic converter anyways and I was starting to strip the bolts with my Ryobi tools.
It turned out to be an electrical connection issue! The mechanics noticed that the rear lights were getting dim, so they found out that the previous owner/mechanic had put too much dielectric grease in the connector. It now runs perfectly fine!

 

Yes, you use dielectric grease instead or regular grease so you don't get any shorts because dielectric grease does NOT conduct electricity
So you never put it inside a connector where you WANT electricity to be conducted, lol
Around the edge is fine, but not IN the connector