I've been working on a '98 LX I recently got, bringing it back up to snuff with emissions, suspension, appearance, etc. It has the 4-cyl with 5 speed manual transmission.

The car has about 178K miles, and it runs actually pretty well; I've noticed that when I shift, the engines don't drop down when I let off and gas and depress the clutch pedal.

I can't remember if this is normal for the car (its been many years since I owned a Honda manual transmission), but it makes matching engine speed difficult.

[I seem to recall there used to be some sort of solenoid that was designed to do that, but this seems a tad aggressive]

I searched the forums, but I couldn't find a reference to this.

 

First, go through the base idle adjustment (look in DIY section). Part of that might be due to the IACV's control action being a bit lopsided vs where it's supposed to be.

There isn't a separate valve for this, it's all rolled into the IACV and programming.