gutted cat for dinner

[HOUSTON]

Chris Dyer wrote: 

So, for fuh-evuh I've had an un-diagnosable, intermittant high idle
problem on my '87 5kcstq. Many an audi wrench couldn't figure it out. 
Latest guy is thinking bad cat. It does make a tinny-vibration noise
sometimes (I assumed it was just a bad hanger or something). It kinda
makes sense; bad cat sends bad info to O2, the confusion begins. 
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Burl Vibert wrote:

That diagnosis seems a bit out to lunch to me. I've only ever seen cats
plug up, if that happened you would see a huge loss of power at high
rpm, probably not an idle problem. Also I can't see how it would be
intermittent. How high is your high idle? 
Burl Vibert
1987 5000CSTQ 
1983 Coupe (anyone have a spare tranny?) Kingston, Ontario 
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JCS_TX wrote:

Chris, did you change the ISV?  Do you have any vacuum leaks?  Remember
simple solutions first.  A new cat. from www.discountconverter.com is
about $100 which is a deal.   My .03 cents