This started about three to four weeks ago. I noticed when I am stopped at a light that the idle will go up to about 1100 rpm's and then after a few seconds will come back down. It contunues to do this all the time. Of course when I'm driving I dont notice this. It seems to do this whether I am in gear or not. Just wondering if anybody had any suggestions on what I could look for.

 

Clean IAC valve.
Check for vacuum leaks.

 

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The Idle Air Control Valve (IAC) is an electric solenoid that controls the amount of air which gets passed a closed throttle at idle.

Ford used a couple of different but similar looking IAC valves in 1995. Here is a picture of one IAC: http://www.rockauto.com/ref/Motorcra...tml?CX1846.jpg (The Forum software will take you right into the www.RockAuto.com catalog. So cut and paste the link into your browser to see the picture or look under Emissions in the catalog and hit the More Info buttons to see parts pictures.)

The black cap on this style IAC might give access for cleaning.

 

Ok guys, I finally got around to checking this out. I got 9 ohms from the IAC valve. According to my book this is in spec. I did remove it anyway and checked to be sure the actuator inside moved freely. Cleaned it up as best I could and gave it a small shot of CRC3-36 and wiped it out again. Put back in and warmed it up and drove around for awhile. Seemed to be ok or at least what it used to be like. I did however move the vent setting around each time I stopped from AC to off and defrost to off to see if the idle changed. It did but it didn't feel like the car was pulling away from me like before (doing what it is supposed too). I will continue, of course, and see if this happens when I'm on a longer drive. Someone said the resistance should be 20 ohms or more. So it could still be bad and maybe its just behaving for the moment. Thanks again, and if it does continue I will be back.

 

Check also to make sure that neither pin in the IAC is grounded to the IAC case; you should get "infinity" ohms (full scale needle deflection on an analog meter)
IAC's often respond to cleaning even when they appear to be in spec and not stuck. I think this is because, even though the actuator rod moves, it isn't actually sealing properly. Once cleaned off it can seal again.
From reading your post, I think you're saying it's OK now except idle rpms move some when you switch in the AC. I'd consider a momentary change normal, after all the valve has to react to the additional load you just dumped on the engine by putting the AC on during idle (several extra horsepower in an instant) but if the idle starts flaring again or dropping off just replace the valve.
I think you've identified that this is the problem and the original one lasted you 10 years!

 

Thanks Allan, I'm pretty sure it is also. If it does come back and start doing it again I will change it out. Appreciate the help.