Renault megane cutting out?

My 2003 Megane 1.6vvt starts and runs fine, however when i get stuck in a bit of traffic the temerature sensor drops suddenly to cold and the car idles irratically and sometimes stalls. When it stalls i cannot restart it, has anyone had a similar problem and know what it could be / how to fix it.

The error code says a problem with the dephaser pulley, but it starts fine with no knocking and sounds good on startup so i'm not sure if this is the case.


thanks alot

Big Al
October 2009