A friend of mine has a problem with her Ford Escort Zetec 1.8 motor and it has a problem that makes it rev up to 1500 rpm and then down to 500 rpm and then up the 1500 and so on when it is on tickover.
It has been in the garage and they said it needed a new the air flow meter, they replaced it, charged £85.00 and it is still the same.
Now they are saying it is the idle valve.
Has anyone got any ideas?