stalling at deceleration

[Efraim Gavrilovich]

The patient: 88 5KTQ.
The symptoms: when decelerating while approaching red light at intersection,
especially after hard acceleration, the RPM drops as low as 500. If not
watched and corrected by tapping at a gas pedal, engine stalls. First time
it happened, I was caught totally by surprise. Luckily I was driving in the
middle lane, so I could duck into the curb lane and stop. Pretty scary. Good
thing that bomb was working. After a few minutes restarted the car and
continued driving. This time I was careful to shift into neutral every time
I needed to slow down and stop. Shifting into neutral helps, no more stalls.
Can anybody recognise the problem and advice on a possible cause? This is
not a vacuum leak as car was recently checked with a smoke machine and
showed no leaks. Spark plugs replaced a month ago. Could that be a faulty
injector(s)?
Efraim Gavrilovich
1988 5KTQ 338,000km (210K mi), 1.8 Bar
1990 90 114,000km (71K mi)
Vancouver, Canada