Heating and overheating issues

Hello,
Last summer my 95XJ began overheating a bit when sitting idling for long periods. Now I'm noticing that if my Jeep sits at idle with the heater on, the air coming out of the vents is not very warm. If I raise the idle, it will immediately warm up. Looks to me that there is not much coolant volume circulating. Could these two (heating and overheating) problems be related? Could the impeller in the waterpump be eroded and not be moving enough coolant?
Thanks,
Mikel

Yup, my 98 went this past summer, original pump... Only way to really find out is to either remove it or disconnect the two hoses and hook them to some clear tubeing and visually see if you have flow or a variation of that of some sort..

If you haven't flushed your entire system in a long time, you might want to try that also.