Help! my 2003 RSX heater issues? when the car is warm it blows cold air at idle, car has to be moving to blow hot air

The idles speed is too low or the water pump is worn. Not as much coolant is being circulated in either case.

Does the temp coming out of the heater change gradually or rapidly? Have you checked coolant level and checked for trapped air in cooling system? How does the coolant look is it nice and clean or is there a lot of sludge in it?

gets hot real quick once we start moving!

Does it act the same if you just hold higher rpms without moving? ?

yes it warms up when we hold the RPM's up

Some things to look at are; water pump, restriction in cooling system, heater controls, slipping belt, air in cooling system, thermostat. Be cautious with this, but with the engine warm have radiator cap off and rev engine a little you should be able to see significant movement of radiator fluid.

Thanks, i will check all of these points.