I found the following on the net. Also, we've been having a check engine light issue associated with the manifold. The car is running so great that we have chosen not to address it at this point. I wonder if that is creeping into this stalling equation..
Fuel Injection Stalling Problems
On fuel injected engines, stalling can be caused by anything that upsets the air/fuel mixture. This includes vacuum leaks or unmetered air entering the intake manifold downstream of the airflow sensor, a faulty throttle position, MAP or oxygen sensor, dirty fuel injectors, or low fuel pressure to the injectors (weak fuel pump, faulty fuel pressure regulator or restricted fuel filter). Like older carbureted engines, a defective thermostat may be preventing the engine from warming up quickly or reaching normal operating temperature. Or, a defective coolant sensor may be telling the PCM the engine is colder (or warmer) than it really is. Any of these conditions can upset the fuel calibration of the engine and cause a problem.
Idle Speed Control Circuit
One of the most common causes of stalling on fuel injected engines is the idle air control (IAC) solenoid or idle speed control (ISC) motor. If the idle speed control device fails to provide the correct idle speed, the engine may die when you slow down or come to a stop. In many cases, the idle control solenoid or motor is gummed up with carbon and fuel varnish deposits. Cleaning the idle port in the throttle body, and the IAC or ISC valve with aerosol throttle cleaner can often solve the stalling problem. If the situation is not improved after cleaning, however, the IAC solenoid or ISC motor may have to be replaced. Check the connector to the device to make sure the connector is not loose or corroded.
