Could be a number of things mate. Have you had the cat checked to see if it is blocked? Also perhaps the coil pack could be failing also and perhaps although unlikely a blocked fuel filter.

 

what is the condition of the fuel pump?
have you checked the gaps in the plugs?
maybe there could be a vacuum leak on the inlet somewhere.

 

Just a guess, how about the air flow meter?

 

that could be the fuel pump on its way out, get it to a garage and get the fuel pressure checked out, my esc gti started doing exactly the same thing

 

ok i will be checking fuel pump pressure, cat for blockage, air flo meter, coil pack and i will be fitting new plugs and icv this weekend ah the joys of motorin eh

 

Are you using BOSCH plugs ?, are your plugs leaking, corona discharge is ok but no streaking, zetecs are famous for this, due to the humidity inside the area where the plugs are.
Probably 50% of the bosch plugs I've used have leaked within the first few hundred miles, it's also possible the plug boots have slight tears on the inside where people don't use SILICONE grease on the inside of the boot where it goes over the plug, it should be used on zetecs.
tabetha

 

fitted new plugs and icv tday and its seems to have made 100% improvement it pulls a lot better now and the cough it had about 4 grand seems to have gone, feels like a different car thanx for all your imput people