Jim Farmer from Iowa City wrote:

>While bleeding air from my cooling system, I ran the engine at about 2000 
>RPM by putting a dime in the throttle linkage.  After it warmed up good, 
>it started periods of running at 2100 and then dropping to 1900 and then 
>back up again.  It would stay at one speed for a minute or more.

>Later, it surged up to 3600 RPM, but I think maybe the dime moved and 
>openned it up more so unless this sounds unusual to someone, I'll 
>probably ignore it.

I had a similiar problem when i first purchased my 87' Syncro a few years ago.
First, i would check the throttle valve switch.  The location of the switches
varied slightly from year to year but all are located somewhere adjacent to the
throttle body.  If the switch is not adjusted properly, ie:  does not completly
close the circuit when at idle, the control unit is sent incorrect information.
This was exactly the problem with my van.  At idle it would surge back and
forth.  Adjusting the switch cured the problem.  The procedure for adjusting the
switch can be found in the Bently Manual and should be done with a continuity
tester if possible.  Good luck.

Mike