I was driving around 45 mph and slowing down to the sotp . I stopped and sudden the engine shut off and all the light on. I started the engine again and drove off without problems. What caused that? Is it something about IVC and fuel pump relay?

 

Could be battery. Check your battery post clamps and battery tie-down. Make sure they're tight.

 

dirty throttle valve?

does the rpm goes down also if you turn the steering to end stop?

 

The url below discusses engine stall causes. Not MB-specific though.

http://www.allpar.com/fix/stall.html

 

Yes, rpm went down as normal. I took out the IVC (Looked clean) , I cleaned it anyway. I started the engine, no problem. I have not test drive yet. Hope it turn out OK, otherwise, I may change the fuel pump delay. Thanks guys.