Problem:
While on idle either on Park or Drive, engine would stall intermittently. However, as long as you are constantly moving without stopping (for a stop light or traffic jams) the car runs fine. When it stalls, it would not restart immediately. There are other post that describes similar problems, however I would like to share some observations and some trial and error I have done.

Observations:
Observation No. 1 - When it stalls, I try to restart - it cranks but would not "catch on" no matter how many times I try. I give it a rest for probably an hour, then it would start.

Observation No. 2 - When it stalls, I try to restart - it cranks but would not "catch on". This time I pop the hood and restart - it starts! with no fail (90% of the time). But of course, think about doing this at a stop light or when crawling in a traffic jam or approaching a toll booth.

Observation No. 3 - I let the car idle on my driveway while on either Park or Drive, it would stall after I would say 5 minutes (when engine is cold) and much sooner when engine is hot.

Observation No. 4 - I let the car idle for almost 45 minutes with the hood up on my driveway while on either Park or Drive and the car does not stall.

Can anyone suggest what may be wrong?

 

Assuming all normal maintainance items are up to snuff, I would guess a bad crank position/rpm sensor or it's wiring.

 

Or Fuel pump relay.

 

Seems as if the heat is the key.

Repeat Test # 3 but this time, put a Ziploc Bag with ice cubes on
1) the Fuel Pump Relay
then
2) the Coil (or power-stage on the Regina system...what does a 91 use anyway?) Generically, the ignition triggering module.

If the crank position sensor is buried in the engine I'd not think that is the cause...it has to be something up-top.


The idea is to isolate the faulty component by cooling one thing at a time.

Good Luck