William,
    You did not mention if the idle position switch was checked for proper
operation. Another thing that came to mind; do a compression check. One of
the times my 86 failed was due to a burnt exhaust valve. Also, right before
a smog test I always change the oil. They say old oil can hold excess
hydrocarbons, or something like that. I also run a tank full of (gas with)
injector cleaner through. Old plug wires can give a poor spark. And if all
else fails, a brand new catalytic converter will always gives me results in
the single digits. ;-/
Ken Lewis
http://neksiwel.20m.com/