Engine rough at idle when AC is on

[desertrat]

My 98 3.0 Ranger runs near perfect except at idle with the AC on. Above an idle it seems OK. Runs OK until and unless the AC is turned on. (Has to be on a LOT in Arizona). It idles rough, with a slight miss, when the AC is on, almost all the time. I have read somewhere, maybe on this Forum but I cant find it, that the computer changes the mixture when the AC is turned on. Anyone know anything about this? Is there some sensor or something external to the computer that is bad? On rare occassions it will run normal, then start doing it again. Driving me nuts. Also does not want to accelerate smooth out of the idle. HELP!!

 

[Rearanger]

You may have an underlying miss that shows up more with low idle. I'd check your wires and plugs. The computer or a separate idle-up switch should maintain proper idle when A/C is on. Other than that I can't tell you what to check.