1999 classic 4.0
I have fuel to the rail, probed fuses and everything checks out.
It will crank and run for a second and then die immediately, if I try and start it again it will just crank unless I push the gas pedal and it will fire up and then stumble and die when I let off. Crank sensor sound like a good place to start?

 

Before you just throw money at it, when it doesn't start verify you have spark and fuel pressure. However if you have more than 100K on the CPS it should be changed anyway

 

I’ve just replaced the plugs, coils, rotor and cap and a few days ago and it was running like a top. Ran great when I parked it last night. That’s why I was thinking the sensor right away.
273k miles and I have no history on this thing

 

You have already spent some money. My philosophy as a tech in an unrelated industry is start testing so you know where to go

 

Sadly, but because of the crummy parts situation, before you throw any new parts at it ...
​​​​​​ You said you just changed the rotor,cap,and coil. I would look hard àt the new cap and rotor to make sure everything looks ok, and if it does try it with the old coil.
don't worry about the plugs.

 

Here’s a video of its symptoms. Only will start a little if I give it gas. This is after putting a new crank sensor in. It blows smoke now and it’s oil for sure.

 

Update:

Held the throttle a bit for a few seconds and it started, would die if I let off. After waiting 5 more seconds it would idle. Never seen anything like it before. Runs great, turned it off and it idled fine with (still has a slight miss at idle)