Hello everyone, I have a 2005 XJ8 with a rough idle when I turn my air conditioning on. This has been getting progressively worse since last year. I try not to use the air conditioning now because of this issue. I have cleaned the throttle body already last week and it did not help. The throttle body itself is relatively new. I replaced it last year. I did hear about the IAC valve going bad but I haven't seen anywhere on the web that says my particular model has one. I did see that the older XJ8s have one but not the x350s. Looking for any advice. Thank you!

 

A thought out of left field here ........might pay to check your grounds.
Particularly G26 rear of RHS shock tower, G3 under the front power distribution box and G7 left side of the transmission tunnel (inside cabin).

 

Great advice I will check those grounds thank you