I'm thinkin' that perhaps you're seeing a lot of blowby up into the air cleaner. Maybe a PCV valve needing replacement, or perhaps the motor has a grunch of miles on it?

You'll note that the PCV is in the pssgr's valve cover, and a breather tube in the driver's side valve cover goes directly to the middle of the air cleaner. If you were having tons of blowby it could go to the inside of the filter before being sucked into the TBI.

You also might want to pull the air cleaner lid and see how the injectors are spraying. You should see an even spray pattern, fan-shaped with no "globs" of fuel. Maybe you've got a strange-spraying injector which is polluting your filter.

The poor-running when cold might be tuneup-related. Dist cap, rotor, new wires, and plugs usually work wonders on these motors. I'd recommend AC Delco Rapidfire plugs, std or platinum; the little 60-Deg V6 seems to like these plugs.

The "heater box" on the exhaust manifold is part of a "heat stove" system which provides heated air to the TBI in cold weather. A thermostatically-operated vacuum-bleed valve works to move the flapper valve in the air cleaner snorkel to either admit warmed air from the 'stove' on the manifold, or cold air thru the snorkel. Problems here would mainly affect warm-up driveability in extremely cold weather, probably not the root of your problem.

Or, maybe it's time for a 3.4, yeah, that'll fix that air cleaner problem fer sur!!!! <img src="/forums/images/graemlins/evil.gif" alt="" />

Let us know what you find.......ed