98 taco overheating checked basics now what

Once you get a leak in a pressured system, nothing is going to work right. As the truck heats up it will force the liquid out of the leak instead of cooling. Without the pressure to keep the coolant from boiling, it will do so and it will also become less efficient overall. At the same time, any coolant moving past the leak will also suck air in and it doesn't take much air to cause an air lock. Assuming the leak happened while the engine was hot, and pushing coolant out, as soon as the pressure started to drop its going to start draining from the highest point in the system, that's your heater hoses. Air lock again. Once the engine actually cools, the water level will drop again, sucking in even more air. So a bigger air lock will develop. As you get more air in the system your water pump will lose efficiency, it moves water and flat out can't move air. So even more heat etc. Continuing to drive with the engine not being able to rid itself of heat is going to lead to blown head gaskets or worse warped heads. Once that happens you're going to see a lot of bad happen pretty quickly.

Short story, a crack in your radiator is something you want to fix asap.