Hi there

My Octavia 1.6 2010 has the following problem

Sometimes when idling the revs rise and fall on its own and the car shudders a little like it's going to cut out.

No error codes on three different diagnostics...

Thought it was the egr and got it replaced

No change.

Dealer doesn't have a clue what it is.

Help!

Anybody else have this problem

Mike

Have you tried a hefty dose of injector cleaner and an 'Italian tune up' aka a good thrashing?

Any weird/loud squeaking/squealing from the engine bay?

Sounds like an injector problem. As mentioned above try a heavy duty cleaner in the fuel such BG244 or Archoil AR6400-d. If that doesn't work then visit a diesel specialist for the injectors bench testing.