Check wiring to/from the temp II sensor.

My guess is that a previous owner incorrectly made adjustments, i.e.
the big screw on throttle body, to compensate for a flaw in the idle
control system and-OR a flaw at the temp II sensor or wiring to/from
it.

If it were me, I'd unplug the IC system then follow the Bentley timing
etc. procedures and see if the engine will idle.

If I recall, the yellow plug at firewall will disarm the IC system.
(it disconnects power to the IC module)

plug shown just right of centre in this image:

https://lh4.googleusercontent.com/-w-xliMMxwo4/URlSA5NfVvI/AAAAAAAAG5U/8X7jRqzx3s8/s640/Fuel%2520line%2520pics%25202.jpg

Neil.

On 10/16/14, Stuart MacMillan <stuartmacm@gmail.com> wrote:
> Just got my son's "new" '87, and we were told by the seller it had an idle
> problem.  He's driven it about 200 miles with nothing more than a bit of an
> idle surge once in a while, but now it won't idle at all cold, and when it
> warms up for a couple of minutes it races up to 3000 rpm and stays there.
> Restarting doesn't help, and only when I unplug the idle control valve will
> it stop (die).
>
>
>

> this?  It seems odd that an engine can run at 3000 with the throttle
> closed!

--
Neil n

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