my mondeo keeps firing on 3 cylinders now and then?

ford mondeo 1.8 16v on a M reg
my mondeo keeps firing on 3 cylinders now and then why??????? oil,plugs,filter,air filter and leads all changed but still missing !!not sure wot u mean on electrics what could problem be? any ideas Stevie Watson all ideas greatly received mate

Glen Burbridge, November 2004

DAVE YOU WERE WRONG MATE SORRY TO SAY THIS CAR TELL ME WHAT GRADE ENGINE OIL YOU USE THIS SHOULD BE A ZETEC OIL A GRADE THAT IS 5 BY 30 THIS PROBLEM IS CAUSED BY THE VALVES STICKING

ANDY, February 2007

i had the same problem it could be the coil (where your leads come from) or the engine managment side of the ecu could be faulty new ecu is costly but you can get one at the breakers

Dave, November 2005