1993 Lumina 3.1L coupe problems

Car has been progressively getting worse last week. Now will not start except to fire long enough to rev up and then die. Will occasionally sputter for a few seconds before stopping.

Also getting backfire through intake during cranking.

Cranks very fast IMO but I am told this is normal for a 3.1L, they crank fast I guess...

I pulled codes, nothing but 12's...

I checked for spark and there is spark. I can smell fuel and I know it's getting there because it will fire and rev up before dying. Fuel pump comes on as needed.

Car has 132K or so.

So far I have been told to check the gas filter, computer, timing chain, coil packs, and catalytic converter. Any ideas?

look for 3 wire sensor at right side of radiator unplug it and see how eng runs if 2 wire sensor then most likley bad ecm

Gas filter flowed well, was clean coming out both ends...

Computer is only showing code 12's, car runs FINE when cold. Once fully warmed up and parked, does not like to restart.

Removing the sensor wire to the coolant level sensor did nothing at all except disable the low coolant light during bulb tests at first start. I didn't think it would make a difference. Maybe you shouldn't recommend people do that anymore. The 5-10 minutes it takes to walk outside and pull it and then start the car is probably all it needed to cool off enough to start.

So I'm thinking, it backfires and pops...clogged exhaust? The exhaust pulses seem weak out of the tailpipe compared to my 4-cylinder Century. So maybe a clogged cat, which was the idea of my roommate who knows jack squat about cars and only repeated what last item was repaired on his parent's van when it wouldn't start hot.

So I beat on the catalytic converter with a large hammer to break up the crap inside and let it settle to the bottom.

Drove it for four hours, hasn't had a problem restarting yet, I told the owner to go get a new cat. When she has $150 or so she's going to do just that. In the meantime I told her to let her car cool off in between driving, and if she needs to make a bunch of short trips, to take a taxi.

She has Colorado tags but lives in Texas, and if she can get away with that then she can get away without going through inspection here, so emissions be damned, maybe she ought to weld in some straight pipe.