Engine shuts down
 

My 2008 SAAB 9-5 (118K miles) intermittently shuts down while driving. It will immediately restart. I've replaced the Direct Ignition Cassette, Sparl plugs, Crankshaft Position Sensor, Coolant Temp. sensor and the charge air bypass valve. Took it for a 20 mile test drive and it shut down, again. Can anyone give me some other possible causes? No codes show