that can be any number of things, a bad fuel filter, a bad fuel pump, it can be electrical, air. there are 3 basic elements that make a vehicle run: Air, Electricity, fuel, you take away one of these 3 items and your can will run very crappy or not at all. Start with the basics and go from there.
mine had a elec. short @ high speeds or shrp turns it would stall out. wait 5 min then it starrt again or open the hood and wiggle around the fuses in the fuse box facing the car towards the windshield on the right side
check all your vaccum hoses to make sure their tight and not hanging off.
Need to know the year and make, It would help answer.
The first thing I would try would be cleaning the throttle body with some carb and choke cleaner. When they get really dirty it can cause you to stall at slow speeds. On my 93 there is a Crank Shaft Position sensor. Mine started to melt and the jeep stalled at weired times for a week. If your jeep has a lock up solenoid in your tranny and its stuck on, then you will stall at stops Not sure about a 94, but my 2000 would stall while driving at highway speeds. Dealer replaced the oxygen sensor and it fixed the problem.
Not using premium fuel caused that in my 2004 Navigator.
if it happens when you go full throttle or at highway speeds try replacing the fuel filter
only if it doesnt have fluid.
Could be many reasons such as bad alternator, or bad fuel pump.
Brake Booster needs replaceing
On a 1991 Lincoln Continental : I'm not a mechanic / technician but I have never heard of aluminum heads for the 3.8 litre Ford V6 engine So , I would assume they are cast iron
You might need freon
Would have been built for R12, can be converted to R134a.