What is the next step in fixing an intermittent stall? At the end of my rope!

What is your question?

Hi! I have a 1998 Toyota Corolla CE which is MOSTLY great and only has 101,000 miles on it. However, it has been randomly stalling during the last few months, mostly at red lights or when turning the steering wheel all the way. No noise, no shaking-just like someone turned the key and shut the car off. No engine codes. Car always restarts right away. Starter was replaced fairly recently. Coolant sensor, battery and alternator all fine. We replaced the MAP sensor, PCV valve and spark plugs,as well as the idle air control valve.Throttle body is clean. I can't keep replacing random parts, but I am scared to drive the car. Local Japanese car mechanic is stumped. Thanks in advance! Car hesitates or stumbles once in a while.

What makes this problem better or worse?

Usually worse when engine cold, or when car has been driven and then sat for a while.

How long has your 1998 Toyota Corolla had this problem?

About two months