2004 Honda Civic • 1.0L 4 cylinder RWD Automatic • 80,123 miles

Heat very hot when driving. Heat willnot stay hot while idling. Gaugestays up
wont maintain heat Heat very hot while driving but cools down while idling at stop light or standing in driveway.
Had new water pump installed, new radiator cap cabin filters, timingbelt.
January 29, 2014.

It sounds like you have a restricted heater core, I would suggest a flush of the heater core.

Jan 29, 2014.
It sounds like youre not getting enough flow through the heater core. Did you replace the water pump and tstat yourself? If not id take it back to the shop that did and tell them of your heater issue. Otherwise when the car is cool. Take one of the heater hoses loose at the firewall, crank the car and check for flow. This is a line that comes directly from the waterpump. If theres no flow there at idle the waterpump is at fault