Hello my tech Friends, i have an interesting case here. on this 2006 Pacifica 3.5L. So Came in to shop with a complaint that shuts off after starting. Checked DTC's, i think i saw something related to the Catalytic converter or maybe an o2 sensor, don't remember at this point, Anyway car felt like it was choking on gas, i felt that the cat was clogged so i removed it. Saw exactly that, the cat Was blown to pieces internally. Replaced the catalytic converter, Next i noticed that they put a short ram after market cold air intake that sounded like it was struggling to suck air, so i removed the filter end. At this point the cat is on, and the air intake is free to breath. I try to start it and yet it does the same thing but it lasts a few more seconds which allows the PCM to throw an Injector # 4 code. That made sense since it smelled like it was guzzling air, and the o2 sensor (0-1v) 1 is reading 2v+ and the post is reading like 4v?? Next i removed intake, checked compression, all 120- 130 PSI, Replaced complete fuel rail with a good one i had laying around, and replaced all the Spark plugs, because they were burnt to a crisp with the OEM grade Laser NGK ones. So now that i have the catalytic converter bolted on all those parts are replaced i tried starting it again, Now its struggling to idle and its shooting FLAMES out of the catalyitic converter. I think its save to say that its running super Rich, Funny thing is no DTC's now, and o2 sensors are reading beyond normal. sensor 1 - 2V and sensor 2 - 4V .

Any ideas what could be happening.
Good compression. Good spark plugs, Injectors,
Only thing i can think is that this stupid after market cold air intake the customer has on here isnt being handled well by the PCM, or O2 sensors are bad but then again even when i unplug them they read the same thing.