Durango 5.2L ignition fails

Hi all,
I hope someone may know why my daughter's '99 Durango tends to stop running with a warm engine. This has been happening in the last 6 weeks, 4 times. Found out that if I let the engine cool for at least 1 hour, it starts again. Yesterday it failed again but I couldn't get to start 3 different times over 4 hours.

I went back this morning and it started rough and then it smoothed the idle. I drove it home, parked it let it warm up and it just kept running.

I bought the Durango 4 1/2 years ago and the original owner had installed an M1 intake, and MSD 6A ignition setup, headers and he may also may have installed a cam.

In the last 10 days, I replaced the spark plugs, the cap and rotor, installed a new MSD Blaster coil; I replaced the plug wires in May, 2020, and they have 41,000 miles on them. The engine still has the original distributor but I haven't changed the pickup coil. I'm stumped right now, I need some new ideas.
Thanks,
Tony

Is this still using the OE EFI setup? Just wondering since it has an MSD added.I was thinking ignition coil or crankshaft position sensor if original setup.Did you check for spark or fuel pressure?

I had a LOT of trouble with the MSD in my '82 Ramcharger. I had it all mounted in the cavernous area under the driver's seat so no problems with heat. I had it wired so by just switching a couple of wiring plugs under the hood I could be running on the original mopar electronic ignition system. Whenever it died, that was the solution. The benefit from running the MSD was so minimal and the hassle of getting out and changing the wiring so great it made me eventually abandon the system. I suspect the box itself was intermittently bad but I never pursued getting it fixed or installing a new one. Dad had similar problems and had his repaired at MSD as he lived nearby and it worked fine afterwards.

Original distributor, MSD was added on around 2000-04. Haven't checked fuel pressure, but I installed a new pump last November. Spark is good, and yesterday when I checked it was getting spark at the plugs, but wouldn't start until this morning.

I'm debating to install a new 6A box.

the distributor itself doesn't do much like it did on older 318s. No advance can, no advance weights, unless the bushings went bad (I havent seen one off a Magnum engine yet with bad distributor bushings) replacing the distributor itself would be an almost certain waste.
what brands of parts did you use? I had a new cap on a 3.9 in a Dakota recently go bad on me in less than 5k miles. Napa Echlin too. and quantity of miles on wires doesn't speak much for whether they could have a problem.

Champion 7436 double platinum, MSD coil, Standard brand cap & rotor at O'Reilly.

Sounds like injector driver bad in the confuser or maybe bad cam sensor (the flat plate like sensor in the distributor.

Since he said he has spark I agree. But isn't there something about the computer needing to see spark or RPM before it'll fire the injectors? I seem to recall reading something like that years ago.

My friend did some research on this, it maybe the crankshaft sensor. In 2000 it happened to our '91 Cherokee with a 4.0L.

I'm on really thin ice here, but I don't think the plugs will fire without a crankshaft and camshaft position sensor signal.

That's true, the engine sounds like it's not getting fuel. But once it cools down, it acts like it's flooded and starts within seconds.

I'm starting to be inclined towards the computer (PCM) being on it's death bed.

This will be OBD 2, so a scan of codes is a must.
Those MSDs dont have the best track record so that needs to be suspected

Crank sensor on back of pass side of bell housing needs to be considered as was said.
Start with a scanner and fuel pressure check. The aftermarket fuel pumps seem to be built to fail at excactly 1 year now.

Pulled CPS, checked the ohms, resistance was higher than a new CPS. We installed, engine fired immediately.
Thanks again for of the suggestions.

Sock filter below the in tank fuel pump
can get clogged with crud and will “cavitate” the flow of fuel into the pump.
This will cause the engine to suddenly die from near zero fuel pressure,
but re-start and run flawlessly for awhile
after only a few degrees of cool down from being off.