I've been chasing a hard-to-reproduce erratic idle / stalling issue.
Never cut out when cold, only after it got warm from a short-trip and started up again. Would often just start then when I took my foot off gas to shift out of park (97), idle would drop, gasp for air and die. Happened often coming to a stop at a light.
Sometimes would happen for days in a row, then nothing for a week. Sometimes died at 20 mph when I took my foot of the gas.
Tried the usual suspects, new Stepper, new VSS, new TPS etc.
Turned out to be a really easy fix in the end. Replaced both the hoses shown in green in the image. I believe the primary culprit was the one that runs from near the oil filler cap to the plenum (on right in picture), it was lined with thick oily gunk. Flushing it made a considerable difference - replacing it solved the problem all together.
Been running great for a month now with no dips in idle or stalls in sight. Fingers crossed.
(Picture is a GEMS sample I found online - not my actual engine - obviously