1996 sunfire studers when driving

Where did you buy the alternator? Charge the battery and have them both tested.

try hold up the key while starting, shot in the dark. if it startes remove extra items off key ring

contact the factory and they can usually connect by satelite and reset your theft device. it happened to me before.

You have an ABS Braking System Malfunction

Just sillly for a professional to say there is nothing
wrong

Your car is not safe to use at all

Need a different repair shop & make sure they
underdstand all the details of the issue & they
write down what you tell them

I never recommend a dealer, but in your area that
may be an option. Don't take it back until they drive
100 miles with no issues

Bad fuel pump.
If so,have to remove the fuel tank,to replace pump

Most often that is a symptom of a fuel pump beginning to fail. As it runs, it begins to overheat and bind. After it cools down, it frees itself up and then works again. However, the same problem can also be caused by a crank position sensor going bad.
Next time it happens, turn the key on while someone listens to hear if the pump (inside the tank) is running. If not, likely that's what is failing.
Crank sensor can be tested with a digital ohmmeter, but many times it will not show up as bad until it completely fails.

This is most likely an ignition module located inside the distributor that is failing intermittently, this truck should be brought to a Auto Zone to check for trouble codes that are stored, they do the code check for free and this will help narrow down the problem so you won't be changing parts that are not bad.

Fuel Pump

If this happened all of a sudden, It sounds like a Vacuum leak. I would inspect the vacuum hoses for brakes or cracks. Is the Rpm too high to test drive and see how the vehicle is running?

Next time disconnect the negative and not the positive if it ever happens again. This happened due to the PCM needing to be reset.