System Shutdown

[airmo3000]

HI I have an issue with my 1999 RX300. About 4 times so far the engine has completely shutdown and the electical system shutdown except for the annuciator lights under the instrument cluster while the car was stopped with the engine in gear usually at a stoplight. The engine revved slightly between 500 and 1000 RPM every time right before it took a dump. It started back up without hesitation (which is good at least) and then proceeds to work fine until the next system shutdown. This is a seemingly random event which doesn't occur often. The diagnostic device that checks codes that a repair shop (not Lexus) used reports not error codes of any kind. The electrical system checked good including the battery and alternator and connections. Anyone hear of this problem and/or have any solutions? My wife is getting on me for this one.

Thanks

[92Lex]

Have a shop actually diagnose components. Could be the computer, MAF sensor or idle air control valve.