My idle speed is high/slow to react, and sometimes it feels like the brakes are fighting the engine. The truck idles in neutral at 900rpm and in gear at 700rpm, but when I stop at a red light, the idle gradually falls from more like 850rpm (sometimes more) and usually doesn't reach 700rpm for several seconds (never at a short stop sign). If I shift into neutral from D, the idle speed will leap to 1,100rpm. It actually does this when I shift into R or D from park, too, which is disconcerting and is eventually going to cause a fender bender. I replaced the IAC, which helped, but there's still something wrong. The throttle plate and cable both seem to be in fine working order. I sprayed carb cleaner for vacuum leaks under the hood but couldn't find any. Are the front hubs and transfer case vacuum operated? I have the Ford PC/ED manual on order, so I have no idea what else to look at for idle speed.

 

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