heater core 1998 dodge dakota

Sounds like the heater core is plugged up with corrosion (Low heat output). Back flushing it will get some of those flaky chunks out, and probably open up the corrosive hole that is already there. My Guess is absolutely. The hole is going to need to be fixed. With the age on the vehicle, you could try some "Stop Leak" After the flush.

Just replace the pump, that stop could clog your whole system...