Is it only at idle that you are experiencing problems?
If you switch the A/C on whilst driving to you have any problems?
It sounds like you may have a problem with the idle up control valve not adjusting for A/C operation. The idle is generally adjusted by the idle air control valve but there is an additional air supply added by the idle up control valve with A/C on.
I have added a troubleshooting guide for a problem with the idle up control valve.
If the problem is with the idle run through the guide and see what you get.
Any questions on the testing procedure please do not hesitate to ask.
Images (Click to enlarge)
Thursday, February 13th, 2020 AT 11:26 PM