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Re: odd idle problem

I'd second that opinion. BTW the reason it surges is because of the decel
valve. The decel valve is invoked if the ECU sees >1200 rpm and closed
(idle) throttle position switch. Hence the surging.  The way you can verify
that it is the ISV is to remove it and block the ports and start the car.
It should idle low. Mine was about 600rpm.
           Michael & Portia Loeks
           Warren ,Oregon U.S.A.

 Current fleet for those interested:

 1986 Audi 5ktq - Tornado Red/Fuchs/1.8bar 
 1985 Toyota Celica GT-S Convertible
 1991 Ford E-350 (Former Ambulance) 
 1984 Ford F-350 Flatbed

> >At idle, especially when cold, it idles normally near 1000rpm, then
> >surges periodically to 1500-2000 rpm, then drops back.  The rate
> >is maybe 2-3x per minute.  
> Sounds like the idle stablizer valve.  That is on a 5k though.  Not sure
> about the 4k.  Exact same symptoms though.