Maybe valves sticking a bit,which was an issue with some until 2006 models?My 2001 zetec occasionally did the same but engine never failed in 120,000 miles ,and four years after selling,I still see it pottering around.

Other jobs were new front brake discs/pads,rear wheel cylinders/shoes,all metal brake pipes and rear hoses,fuel filter,heater control valve....and of course cam belt at 100,000 and yearly engine oil and filter(applicable to my mileage) +air filter element replacement.Usual wear&tear typical of this model/service stuff.

Re it missing...also check under bonnet in the dark for tracking from HT leads and dizzy cap.These sometimes need replacing.Never replaced my leads but did the cap and rotor arm.Spark plugs burnt down a fair bit so treated it to a new set,which improved economy no end ,and no doubt put less stress on the ingnition system.

HTH

Edited by tdc on 02/04/2013 at 12:10