The Symptoms are....
 

Poor idle with plenty of 'hunting', bucking at low RPMs - kinka like the fuel injectors are sputtering, and a rotten egg smell sometimes. Redlines OK, but I think I can still detect the sputtering between 2000 ~ 2500 RPM.

This is on an '88 n/a convertible, with under 50,000 miles. It's all stock at the moment. I bought a new fuel filter today, and some Chevron Tecron injector cleaner, but I'm not too optomistic. My next guess is water in the fuel tank maybe?

What are the next steps in troubleshooting here?

Thanks!

A/.

Clogged cat(s).

yup, that would explain the smell and the bad running condition.

The fuel filter is a good place to start also. Switch that and see what happens.

Clogged cats would almost be a good thing, 'cause I plan to replace the exhaust next spring from the manifold back.... It is a low mileage vehicle, very well cared for and in almost perfect condition, but I suppose the cats could become clogged after 14 years.

Thanks!