total loss of power zafira 2.2 auto (2007)?

Driving along the other day i had total power loss.....not even limp mode....alternator, engine oil light and exhaust emissions light came on.....turned off then on again and fine....that was about 3 wks ago....had dyagnostics done and alternator checked....both fine...any ideas as im due to be using the motorway for work soon and dont want this happening in the fast lane ?!!! Its a zafira design 2.2 auto 2007