Ugh.

It ran better for about a day, but is now back to it'* old tricks.

Sounds like the whole TB might need a cleaning, thats what happened to me last fall, 3 bolts, 2 cables, and 3 sensors to pull off and you can take the wole thing out and clean it up with throttle body cleaner from autozone or wherever

I think I'll give that a try, next. Any specific recommendations for the cleaner?

How does this happen? My L27 with the same year has 213k miles on it. My throttle body was very clean when I took it off the manifold for the first time last week, and while there was some charring around the are where the IAC is located, its never given me problems and the car has started and run perfectly fine since I bought it with 61k. Is this a common issue? Is there a way to prevent some of this charring and clogging?

I think I just got like STP or something, anything made to clean the throttle body should work, it blasted all the carbon off pretty well then I did a little scrubbing with an old towel

xtreme, the only way to stop carbon buildup is to disable your EGR because that is circulating that exhaust gas through the intake to burn a little cleaner

Glad to hear you solved the problem but why did you buy a new one? Throttle body cleaner, an old toothbrush and some time would have done the same thing? Did you happen to see if your throttle position sensor is still working ok?

also, it might not hurt to check for a vacuume leak?

I have the throttle body cleaner, but when I purchased it and asked the auto-zone guy who sold it to me if there were any special instructions/precautions/whatever I should take when removing and cleaning the throttle body.. He informed me that I would also need to purchase a little plastic gasket thing (Cannot remember the technical term...). The plastic item runs around $40; I can get it within the next couple of days. Do I actually need this item, or was the auto-zone man just screwing with me?

The car has begun displaying some new interesting symptoms.

It still drives just fine once you finally get it started and into gear, but if it sits in park for 5 or more minutes the temperature gauge slowly begins to rise.. Much more rapidly than it should. The battery also begins losing voltage, I saw it drop all the way down to the "8" on the gauge. Cranking the defrost seems to slow the progress of the rising temperature, but does nothing for the battery. It does this indiscriminately whether the car is in park, neutral, or in drive with the brake on. Once you get it moving down the road, the gauges return to normal readings.
My car has always stayed around the 200 degree mark on the temp gauge and around the "14" for the battery gauge until today.

I think problems have begun compounding... When it rains, it pours, right? Haha.