Idle woes

[fivespeed3.0]

I've got a 2000 Ranger with a 3.0 and a manual transmission. Recently, when I put in the clutch to coast to a stop sign, especially when fully warmed up, the idle would start out at about 900, normal, but then sometimes it would drop to about 400, go back to 900, back to 400 and so on, cycling between the low and normal idle a few times before evening out at about 900. I don't hear any vacuum leaks under the hood, but am going to take a closer look this weekend. Otherwise, the truck runs great. Any other ideas?

 

[TomB1269]

IAC (Idle Air Control) Valve, manuals use it when you come of the gas and clutch the transmission. Autos us it only in Park. This basically the throttle sensor whenyour foot is off the gas, and the trans is out of gear.

 

[fivespeed3.0]

I replaced the IAC in Feb of this year, I guess it could be bad again.

 

[goon squawder]

The same thing happened to me except i have an auto trans and i wasnt in park i was sitting at a stoplight and it only happens every now and then otherwise my truck runs fine