> At idle, full warm, you should be 750rpm in Drive. If you're around
> 1000rpm and fluctuating at that, I must ask these questions:

Thanks for your help. More specifically, most of the time I can see
the rpm gauge moving slightly up/down around 750. Other times, when I
bring the car to a stop (hot in drive), the idle is closer to 1000 (no
electrical or a/c load).

> 1) When was the last time the cooling system was drained and refilled?

The cooling system was drained/filled in March 06 by an independent
shop that specializes in Hondas.

> 2) How old is the thermostat?

Original (7.5 years).

> 3) What does the fluid look like when you pull the rad cap (cold!)

It looks normal (green).

> Your wires are seven years old. Time for new ones (OEM, of course). Old
> ones will leak current in damp weather, resulting in a weaker spark than
> what you should have, and worse combustion. Wires that are poor enough
> can cause hunting idle.

I thought I read here that Honda wires last a very long time. Anyway,
the wire on cylinder 3 doesn't give me great tactile feedback (soft
click) when I press it into place on the spark plug. I think it's
engaged, but the others had a different feel when engaging.

> Right now I suspect your problem has absolutely nothing to do with the
> IAC or the throttle body.

Other data points: the rotor and distributor cap were replaced 4 years
ago. Last valve adjustment also 4 years ago.