Chrysler Repair: 1996 Neon Stalling Problem, obd ii, oxygen sensor

Question
I've got a 1996 Ply Neon.  Since June, I have had an intermittent
stalling problem.  This has occured three times so far.  First
time, my independant mechanic suspected potential bad fuel, so
recommend fuel additive. He tested the pressure on the fuel
pump, which was holding more than enough pressure.  Second
time around, dianostics turned up a faulty Oxygen sensor.

After the third time, I held off on sending it into the shop.  The
car restarted after a hour or so after being stalled out.  Some
common denominators with all incidents:  The temperure
outside was in the 90's, and I was  running the AC.  I also
checked for Recall notices, there was one posted regarding
stalls, unfortuneatley my VIN was not included.

After talking with my mechanic, the next step is to check with
potential electrical/ignition problems.  So far, this has not cost
alot.  Wondering if you have any insight regarding this type of
problem.

I thank you in advance for your help here.  

Answer
Hi Scott,
The most useful thing to do would be to see if there are any new fault codes stored in the controller memory. The 1996 year was the one when the OBD-II diagnostics were adopted which lead to a loss of the ability to readout codes by means of the ignition key. Nonetheless it is worth a try:
Try using the ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). Then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. Then send me a 'follow-up' question telling me the results of your readout. By the way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of readout".
I have the troubleshooting manual for the several of the  engines and we can look up the possibilities of what is wrong based upon what fault codes you show.
There is also an essay on fault codes at the site:
http://www.allpar.com/fix/codes.html
which gives the meaning of the code numbers. But then you need to get specific info for what exactly might be the diagnostic tests or parts to replace to complete the repair. If you get the codes, write back and tell me and also say which size engine you have.
If the codes don't readout with the ignition key, then your mechanic probably has a reader and you can get the numbers that way.
From what you describe I would agree that you may have an ignition problem, specifically the Hall effect sensor(s) which are needed to time the spark/injector(s) could be flakey. That should set a trouble code.  
Roland