I can definitely take it to WOT in park if that's what you mean, though it did spit on me the other day when I did so recently, so I'm trying to go easy on it until I figure out the issues.

 

Then it isn't the cat. At least in my experience a clogged cat won't let you rev high

 

It looks like from the pic, you're using a bidirectional scan tool? If so, turn off the injectors one at a time n see what happens. Aside from that, at a guess from what your pic states...the trims, while off, aren't anything terribly worrysome. If they hit-20-25, yeah, I'm thinkin' something more serious. However, I'm guessin' they don't set off the money lite? I would still unplug the upstream O2 sensor n see if anything changes, maybe even remove it altogether n see if the engine runs smoother. Yeah, you'll get a money lite, but the ECM will go to default mode of open loop?/factory preset air fuel ratio. It's also possible that the cat is either in the process of clogging or breaking up. My cat broke up years back. Twas clogged, but not enough to cause severe drivability issues or extreme long or short term trim deviations. I discovered the broken bee hive of the x-cat with the magic rubber mallet. Today, without a cat, my trims are still a little out o' wack, +/- single digit long n short term trims, but quarter million miles do things like that.

 

A quarter million is pretty impressive! I know these engines can last a long time when taken care of. Here's hopin... at 180k now.
Did your LTFT change much after you replaced your cat?

Unfortunately I don't have a bi-directional scanner to check injectors. I have recently replaced the PCM after having condemned the previous due to a faulty injector driver that caused a rich condition.
Apparently injectors can be damaged if charged open too long like that. Also, all that unburnt fuel could have caused more issues, notably some cat damage.

I suppose I could go through injectors and scope them all when running to see if they have pintle humps on the waveforms again.
Maybe this could help get to source of the fuel pressure fluctuations.

I do agree that the cat could be clogged, but not mostly clogged which could explain some things. Before I condemn it I really want to be sure.
I attempted a backpressure test at the upstream 02 port but I don't have the most sensitive psi gauge. I did see movement on the needle but nothing outrageous.

I love to get a catalyst expert's opinion on the 02 sensor data - that downstream reading is trying to tell me something. I've been told it shouldn't go lean when accelerating and it's obviously too high for idle.
Any cat experts out there?

I'm also of the mind that there could be some extra resistance in the 12v feed wire to the fuel pump. I'll try a voltage drop test at idle.

Thanks all!

 

I'm no cat expert, however, once the cat system has come up to operating temp, the downstream O2 should be steady at around .5-.7 volts. Any oscillation in this reading usually portends a failing cat. I didn't replace my cat, just dumped out the bee hive n reinstalled it. As far as testing individual cylinders goes, go old school. Pull spark plug wires 1 at a time to test for a bad cylinder. Or you could unplug the injectors individually.

 

I don't think there is an external fuel pressure regulator and the filter is on the base of the fuel pump on the beasts of our vintage. Fuel fluctuation is always a sticky wicket, but if the lines are all solid, then it seems the only other possibility/ies would be failing fuel pump, bad connector/wiring or bad injector.

 

Voltage drop test over the fuel pump circuit shows it's got good power and ground. Only 60mv drop altogether when warm.
Scoping the injectors, they all show good circuit integrity and they all show identical pintle humps in the waveform so they're functioning mechanically and closing.

I'm suspicious of the fuel pump and filter, so that's yet to be determined. Do I really need to open the tank to find out?
I guess I can check amperage wave of motor and look for anomalies that may resemble a clog.

Honestly, the biggest issue now is the random stalling since it's the most dangerous when driving. Any other thoughts there?

Obliged y'all!

 

I used to have the dreaded inconsistent stall problem. 96Ram 1500/5.2 manual 2WD. Once or twice a month, it'd just die. Started rite back up tho. Couldn't pin it down to anything. Anyhow, several months back, I stuck a cro bar in my wallet n bought a bi-directional scanner for a multitude of problems with my various vehicles. I reset my fuel sync at that time as well. Now I'm not sayin' this'll cure your problem, but since I reset my fuel sync, no more stalls since. On a side note, I know those magic portals of mopar happiness are wicked expensive, but if you can find/finagle/beg or borrow one...give er a try n see if it worx for you too. Also, the price is comin' waaay down on these gizmos, mine cost $828-Launch X431 Vpro from amazon n now there are even newer models by launch x431 diagun,$717 from amazon, that are even cheaper for the DIY'er...like me. Maybe get into a time share style purchase with some friends, this'd bring it down even more.

 

I don't see how the batt temp sensor is going to drop fuel pressure. Pump and regulator are mechanical and if the fuel pump relay kicks on and stays on you should have 49 psi. Unless there is a sticking injector bad pump or regulator i don't see any other causes. But it's possible the evap system is clogged or not working to allow air into the tank but that would take while to happen not just at idle.

 

If the PCM thinks the battery is overheating, it turns off the alternator. Voltage to the pump instantly drops. So, pressure is going to be affected as well......

It seems REALLY weird to me as well, but, I have seen stranger interactions between sensors, and performance problems.