Automotive Forums

I have a 2000 Ford Focus Zetec DOHC.  Upon some start-ups(not all the time) it sputters and jerks violently untils it warms up and then it will drive fine.  I replaced the plugs(Bosch), wires, and throttle positioning sensor that had gone bad.  It still sputtered so I brought it the the Ford dealership to get it checked out(thinking that it was the fuel delivery module that had been replaced 2 yrs earlier).  They ran their diagnostics test and told me that plug 1 was mis-firing!  To my knowledge if plug one was mis-firing it wouldn't just do it upon start-up and why would it do the same thing before and after I replaced all plugs and wires?  Any help would be appreciated before I go midieval on Ford!