Hi, first proper post. Today while driving my 2.5 automatic superb, blue smoke started coming from the exhaust, there is no power unless foot is to the floor and the car judders all the way. Any ideas what it could be? Its due a service too.

Has it thrown a CEL?

 

Blue smoke suggests burning oil, which could have messed up the lambda(s) and/or the cat, and hence put it into limp mode.