I don't know much about the revving problem but I can tell you what a
fly wheel is.  It is the huge cog at the back end of the engine that
turns the smaller cogs in the gear box.  It is the main driving cog
that moves everything through to your driving wheels.
As for the revving, I have a 99 Ford Ka that has a similar problem to
your car (not as extreme) and the problem is a faulty throttle control
sensor in the oxygen inlet manifold (comes after the air filter).
Don't know if your car has this...I assume it does.
Dan.

First of all I would forget about it being the flywheel - the only
ones that tend to give any bother are the dual mass ones which are
only fitted to the diesel engines as far as I know - at least on Fords
anyway - it is not a big cog and it doesn't`turn the smaller cogs in
the gearbox !
If it is like Fords I would think it would be the fly by wire throttle
body giving the bother - we have a problem with poor connections on
them sometimes - if you can get at the multi plug try disconnecting it
and reconnecting it to see if this helps - if not you may be looking
at a diagnostic check !
                                  Mike D.