Long sad story.... I blew the 5.9 like 3 years ago, swapped in a Ram 5.9 magnum. Ran great for 30 miles until the torque converter puked. A few months ago I fixed that. Drove it around the yard. Everything was normal.

Now it won't run. If I turn the key to RUN a couple times and let the fuel system prime, it will turn over. But it dies after a few seconds of idle. If I spray some ether down the intake, same result.

Troubleshooting:
I have verified fuel pressure at the fuel rail.I have measured 11.9-12.1ohms of resistance across all injectors.
ASD and Fuel pump relays tested good. (75ohms across the main tabs)
There is 5V at the MAP sensor when key is ON.
All spark plugs look free of corrosion, but a coat of black soot evenly covers all of them(unburnt fuel?).
Spark plugs, wires, distributor, rotor button all have less than 50 miles on them.
Fuel pump/filter have less than 50 miles.
It has almost a half a tank of fresh gas.


Any ideas where to look next? I have been searching forums and my FSM for anything else I missed.

98 ZJ 5.9 V8 NP242

 

Update: I tried to clear the security system by turning the key twice in the door lock..... Jeep started.
I let it run for a couple of minutes, but it was backfiring occasionally. I double checked all spark plugs/wires. All good.
Next morning I go out to start it again, and it fired right up, but it stalled out after a few seconds.
Any ideas?