1992 F150 balks and stalls when it gets hot

The alternator only maintains the charge of the battery, has no effect on overheating. If the engine overheats greatly it will balk and stall. You're destroying the engine.

Determine the cause of the overheating problem and repair. Also, do not use plain water in the radiator. The coolant boils at a higher temp. Using plain water can cause an overheating problem and through evaporation a loss of fluid.