'91 Ford Taurus:Can't figure out why it is smoking badly

What color does the smoke appear to be?
Black
White
Bluish

If its black, then your fuel system might be out of trim. If it's bluish, then you're probably burning oil. If there's nice clouds of white smoke, then you might have blown a head gasket. From what you wrote, the latter seems the most probable. Let us know for sure the smoke color though.

Unless you are operating in constant below freezing outside temperatures (in which case a certain amount of white steamy smoke is normal), I would suspect a cracked head or blown head gasket. A farther question. Does your vehicle have the 3.8L V6 in it? I think blown head gaskets were common on them in the early years. But just to make sure, you should check a few things. Do a compression check of all the cylinders and compare them, keep an eye on the oil, sometimes it can become a creamy white with blown head gaskets. And check the cooling system to see if any exhaust is escaping out of that. Sometimes pulling the spark plugs will give a clue. They can tell a lot about how the engine is doing. I hope this helps. Of course the only real way to know for sure is to take the heads off.

Pull the oil dipstick out, if the oil is creamy white, then that is a good indication of a blown head gasket or a cracked head. The creamy white oil is a result of water mixing with the oil, and in the case of a blown head gasket. Coolant from the coolant system. Often seeing creamy white oil around the oil filler port is just from condensation.

The heads are the "caps" that go over the tops of the cylinders. On your engine, the 3.0, has two heads and six cylinders. Each head is bolted down over the tops of three cylinders.

From your view standing in front of the engine compartment, one head will be in the back covering three cylinders, and one head will be in the front covering three cylinders. You can easily trace to where they are by following the spark plug wires to where they plug into the spark plug.

All six spark plugs, three in front and three in back, are bolted right into the heads, and if you unplug the wire and remove one of the spark plugs you can shine a flashlight right through the spark plug hole built into the head and into the cylinder. The good news is that they're so easy to find.

The bad news is that the heads take some doing to remove. You would need to remove EVERYTHING from the top of the engine to reach the heads. Fuel system, ignition system and emission components. As well as such things as the intake manifold, alternator, timing chains, etc. It's not difficult, just time consuming. That's why it costs so much to take to the shop.

I'm sorry this is so lengthy and detailed (I just read through it myself ? ). I hope this helps. I would imagine the repeated stalling could be caused by a cracked head or a blown head gasket, however before you put too much work into replacing those components, take some time to perform as many tests beforehand to make sure. I would even recommend getting a mechanic to look at the car since we are not able to. If it's something simpler to fix, you'll want to know about it before you tear the engine apart.

Double check the sealer you plan to put into the engine. Just to make absolutely sure it's ok for the engine. Keep us posted and good luck!

Anytime! It's always nice when it turns out to be an easy repair.