For the sake of anyone else who may someday experience this difficult situation, my car developed a stall problem overnight--actually after having the oil changed on June 20. There were no warning signs, nothing. After paying for the oil change, I went out, and car would not run. Did something happen in the shop?
It took nearly 4 months and a total of 3 shops to resolve it. Initial diagnostics were not exact as non-defective parts were replaced such as the air idle control motor, ignition control module, and crankshaft position sensor. After that, at the last shop, the screening involved intensive testing over several days. It was found that there were no bad cables or connections and no bad air flow sensor. And, the already replaced items appeared ok and could be ruled out.
Apparently moving up the electrical feed line, it turned out to be the ECM. Replaced the ECM. Problem solved.
Well, not so fast. Car was ready to go and all of a sudden, when I came to pick it up, error codes came up. Upon more testing, the new (remanufactured) ECM was defective. Had to get another, replace, and test again. It is now home in my garage. Almost scared to drive it. What next?
Not sure how much this will all cost, but it was plenty and I don't even have the bill from the last shop yet. It's a small concern compared to a stalling car though.
This may not be of much help, as many things can cause stalls. But, if it helps one person, it is worth writing about.