1996 Ford Taurus stutters& stumbles

Sounds like you have a cylinder not firing.
So the unburned gas is getting to the cat, and the cat is burning it off, causing it to glow red.

You’ll need to do a load balance test to see which cylinder is dead.

Have the engine idling with a low RPM tachometer hooked up.
Remove one spark plug wire,
Make note of any change in RPM.
Reinstall spark plug wire and move to the next one.

When you get to one and the RPM doesn’t change, that’s the bad one.
Now you know where look, you just have to figure out why that cylinder is not sparking.

Remember spark plug wires can have 40,000 volts in them. And the electricity can jump about 1 inch at that voltage.
Take precautions and use the proper tools to keep yourself from getting shocked.

PS, most Dwell meters at auto part stores have a low rpm range on them, and they can be bought for about $10.

Good luck

Anything is possible.

I'm a GM guy, but the way I understand that coil pack works, it's basically 3 individual coils put in the same box. Each coil fire 2 spark plugs each time it goes off.
One cylinder at the top of the compression stroke, and one at the top of the exhaust stroke.

So I bet (i didn't look up your firing order) but I bet if you find one dead cylinder on the front, you would have the corresponding cylinder on the back would be dead too.

Can you get to the coil pack for testing load balance?
Or if nothing else, at least do the front 3