When the idle control valve is replaced does the ECU have to relearn the settings?

 

Yes.
The IAC is a very important part to the operation of cold starts , hot starts, load takeup control for A/C, lighting and power steering loads changes plus deccellertion close down..
To do the relearn the quickest way, disconnect one led from the battery for a few miniutes as enough time for the computer to lose all stored changes to it's operating tables.
Reconnect and do a 'cold' start, turning lights on and A/C/heat/fan etc for max cold loading while recharging the battery.
Motor should go to a high idle then come down to normal idle as heat builds.
Let fully heat then do a drive about 5 miles out and back.
Do a couple hot restarts to load the motor with battery recharge load.
If there are no other faults, starting and running under all conditions should be perfect.
The procedure will have made the PCM handle all the loading it would normally see in this short time and continue to fine adjust over time..
Good luck.

 

Thanks Lots

Thought that might be the case. First time I drove it didn't see any improvement.
Today it seems much better. Will try your suggestions and see how it goes.