Stalling on deceleration

[n-engelbert at terrans.net]

My new to me 200q20v has begun stalling intermittently with the clutch in
when rolling to a stop.  From the archives, my bypass valve is likely bad,
but I want to be sure.

The behavior usually doesn't happen when the car is cold.  If I try to
catch the idle on the way down via the accelerator and then let off, the
car will still stall.  Sometimes the car will drop to 200 or so rpm and
then work its way back up to idle.  Usually this drop below normal idle
speed is accompanied with alternator belt squealing when trying to bring
the car back to ~1200 rpm manually.

I can try to be hard on boost and drop the throttle/push in the clutch and
see if this causes the stalling.

If I restart the car, the idle problem seems fine for the first one or two
stops, then it comes back.

The only other thing that I've noticed, and I'm not sure on this, is that
the stalling seems to occur when the radiator fan is on, although I've
never had the car stall totally when the fan comes on.

Also, with the climate control on, heat or AC, I get an intermittant
squealing from the front of the car that lasts maybe 3 seconds.  This is
accompanied by a slight loss of power.  Yesterday when I engaged the AC,
the belt squealed a lot and then caught.  Am I just looking at
tensioning/possibly replacing the compressor belt, or do the compressor
clutches fail and slip as well?

Thanks!

Nathan Engelbert
83 UrQ 900453
89 90q
91 200q20v