Hi I have a Vauxhall Corsa that was running very badly I have changed the fuel filter. It was very very dirty a lot of black gunk came out. It it now running better at high speed but when I stop at a junction it will not rev again and dies. It restarts very easily and as long as I am reving it it's fine but it will the same at low speed or idling. Also if I start it it fine but if I leave it without reving for a about a minute it will not rev and stops. Any help would be most appreciated cheers.