MTG

I have an intermittent problem of my 2002 Chevy Impala with 87k miles stalling. It usually occurs after 5-10 minutes of driving. It's also died while in idle. It's happened three times while turning; once right and twice left. Also, while stopped at a stoplight and once when in idle in my driveway. The catalytic converter was replaced, new spark plug and wires. It has a new battery, mass airflow sensor, fuel pressure regulator, and fuel filter. Fuel pump is giving me constant 42 lbs of pressure. It throws no codes. Two separate shops tell me they can't find anything wrong with it. I can go months without it happening but if I don't run the car for a day or two, it happens more often. When key is in the ignition in position two, the dash lights come on as usual. The local dealer on the phone says it might be the crank shaft sensor, $300 fix. I'm not sure.