Right so I have just bought a 51 plate ford focus 1.4 zetec se, its been modified and has done 112000 miles with a part service history. its had a Clifford alarm and immobiliser on it which has been a pain in the !Removed! since i got it, think it might be wired in badly.

I've had it serviced had a new air filer, oil filer,new oil and replace the injectors with some different used ones. I had been told that the injectors were not working properly but should be now. The wire going in to the engine head temp sensor is a bit doggy and taped up.

The engine is misfiring pretty badly but still drivable but only just. I was going to look at replacing the temp sensor, coil pack, the ht lens and the ecu in that order to try and fix the problem.

PLEASE HELP what could this be and is anyone else experiencing this??

I would start with the coil pack / spark plugs / ignition leads.

Check for any water in the spark plug whole. Water can drop from the washer jets into the spark plug recess causing misfiring.

thanks mgaking, the spark plugs have been replaced during the service so I presume they would have noticed if there was water in there.

I am going to source a coil pack and ignition leads tomorrow from a 1.6 off a friend should these work fine on my 1.4?

Pretty sure it is the same coil pack on 1.4 and 1.6 (and others) as long as it is the same generation.

MK2 is different I think.

if none of the above recommendations is working for you (spark plugs, leads, coil pack). Check once more the fuel injectors that are working properly, because as you said they are used. The best way to check it is take out the fuel injector from the cylinder that is misfiring and change it with a good cylinder fuel injector. But first start from the simple things.

Let us know how things are going.

right just a little update i have got some injectors leads and a coil pack that i know work. getting them off a 1.6 a mate is splitting and should be fitted in a week or two

I'm not sure if its theses causing the problem though as I drove the car much furtherer today than I have before. It seemed to misfire mostly when I was below 2000rpm and/or lifting off the accelerator quickly

any thoughts?

Right new update fitted the cool pack and ht leads and injectors plus the sparks were done in the service but it's still missing a bit nowagain. My engine warning light has also come on with a p0420 code meaning the catalyst convert is dead.

Could the problems be connected?

misfiring engine will over time damage the catalytic converter. Did you check for vacuum leaks?