Spitting exhaust

[LOACESQ@aol.com]

Hi List,

Anyone care to comment on this one?  My 87 5kcst is idling rough and failing
emissions with a high hydrocarbon reading (around 450 where the limit is 220).
Right now, it has a big red "Reject" sticker on it. The other main symptom is
mentioned in the subject line:  the exhaust from the tailpipe at idle (idle
speed around 750 rpm) is coming out in forceful bursts, with a noticeable
amount of moisture.  It also seems like too much exhaust volume for that idle
speed.  I am particularly curious about this.  For comparison, the exhaust
from my 89 200q, also an MC engine, is soft at idle, like a hair dryer set on
very low speed.

Just installed in the 87 5kcst to try to correct the problem(s), without
success: new plugs (Bosch super trielectrodes W7 DTC), new bosch ign wires,
new cap & rotor, new bosch O2 sensor.  Also, ISV is clean, air filter is
clean, fuel filter recently changed, two 20 oz bottles of Techron concentrate
with the last two tankfuls.

I figure the moisture means the catalytic converter is doing its job, but
working at overtime.  Could it be the cat is, in fact, dead?

Plug #4 is fouling, evidenced by even, black soot deposits.  New ignition set
didn't help.

That's all I can think of.  Thanks for any ideas!!

Adam