i have a 98 2.5 and the heat only works while im driving, also if im stuck in traffic for too long the car will over heat unless i have the heat on. ive been told it may be the water pump, and the heater core could be clogged. a little bit more input would be very helpful as i dont want to spend money and time replacing good parts.

 

Try making sure all air is bled out of the system, a air pocket in the coolant will cause this..

 

whats the best way to bleed the air?

 

how can i bleed the air out of the coolant system?

 

I think it is possibly the temp sensor on top of the water pipe right next to the upper radiator hose. Also you might want to change the water pump and themostat...neither cost that much when you talking blowing a motor if one goes out.