Dying cat...Ack?

[Peter_C_Schulz@ccmail.ed.ray.com]

Hi all!

The last two weeks my Coupe Q has developed a rattle which is becoming more and 
more annoying.  I've isolated it to the exhaust (it doesn't rattle in neutral).  
The rattle occurs when decelerating (steady on gas, then decelerating or 
downshifting ..rattle) or accelerating (step on gas, shift, rattle).  The car 
also occasionally stalls when coming to a stop (taking the car out of gear and 
rolling to a stop, usually this stalling occurs on a downslope)  The noise does 
not occur under steady driving.  Yesterday I put the car on jackstands, and had 
my girlfriend vary the throttle.  I found that the heat shield in front of the 
catalytic convertor was loose and corroded.  This was not making the offending 
noise, however.  The noise appears to be coming from INSIDE the cat. I thought 
that cats were made with an internal honeycomb, plated with platinum.  I don't 
think that anything should come loose, but who knows...BTW the coupe has only 
63K miles on it.  Based on the appearance of the cat, I assume that its 
stainless steel, therefore a replacement is going to be big $$$.

Has anyone on the list experienced this phenomena, and what is your recommended 
recourse ?  Cost?

Thanks.
Peter Schulz
1990 Coupe Q