Could be coincidence and be a cooling problem....

You said "[i].... it has plenty of coolant.[/i]"


This might sound fundamental but.... Be sure to check the level of your "[b]radiator[/b]" coolant (vs. just checking the overflow tank) when cold.

If the radiator is a bit low, my Xterra will run hot to nearly over heating when sitting idling with A/C on. It's only happened twice in 8 years (2001 V6 3.3 4x4). both times I wondered why it doesn't pull it from the tank but it just doesn't :-(

Normally, it runs with the gauge showing in the 1/4 range all the time when operating.