you might have pulled a vacuum hose off
Would need to know if car was overheating before waterpump and thermostat was replaced.
A vacuum leak is one possibility. More info on the vehicle would help.
If the idle is erratic on a 1993 Honda Civic the IACV will need to be clean or replaced. The IACV controls the idle on the car and when it fails the car will not be able to maintain an idle.
The heater cor was replaced but it is still not getting warm
see previous answers, but if it idles high it might be the Mass Airflow Sensor. if your car idles too high for too long and you keep driving it, you could burn out the transmission module (very expensive )
If your radiator isnt leaking and car is having a over heating problem and coolant spewing out. Chances are your thermostat needs replaced. possible the radiator needs to be flushed. But more likley its thermostat
No.
idling too fast - adjust choke
If the thermostat is stuck in the open position, there is no way to keep it from staying open except by replacing it.
When the thermostat and radiator were replaced, coolant could have dripped into an electrical connector or a sensor could be disconnected or damaged. Check the temperature sensor and crankshaft sensors first.
open or missing thermostat
There could be many reasons. Not enough coolant or bad flow, faulty thermostat, low oil. If the coolant freezes then it will overheat. If your car continues to overheat then you should have the coolant flushed and thermostat replaced.