Here is one for the masses.

Car would drive normally, but when coming to a stop, the RPM will drop below idle, sometime almost to the point of stalling. The car will take a second to detect this then recorrect the idle as it comes to a stop.

The Accel inline whine will also change and correspond with the drop in idle. I also notices the MIL light (EVAP #31) will dim as well.

Shifting to neutral and taking my foot off of the brake pedal will help raise the idle.

I recently clean out the IAC, O2 sensor, the filter on the synapse, and will give the EGR (for the 1st time)a once over once it stops raining. Coil pack, plugs, wires...etc are all within spec.

Car is a built 97 ATX with only 73,000 miles on it. RC 270cc injectors at 5-6psi daily, SFMU with 8:1 rise rate set to near stock idle.

I need to drive home to get my datalogger to check what the PCM is seeing. It has been driving fine for the last 5 years with this set up, so this is weird.

Any help is greatly appreciated.

K, I had a similar situation when one of the rubber vacuum lines to the top of the TB was degrading. I think the IAC was trying to compensate for an intermittent leak, and sometimes it would overshoot causing the idle to drop too low. fitty-cent fix