Running like shite

[ned]

Help needed cars started running funny
It starts up fine and drive fine but when it's in traffic or stood on tick over it changes engine note and sounds like it's running on two cylinders and if you turn engine off and leave it to cool a little again it darts up fine and drives well until it gets really hot. Now I've checked plugs, ht leads replaced thermostat which looked knackered anyway, but it still does it. Engine temp seems normal and fan kicks in when it should. Please I really need help.
Oh forgot to say it a 1.6 8v k4m engine on 131k. Hope that helps
Fanks Ned

 

[subtle modder]

Idle controll valve?? Stamped VDO

WONT make it run on 2 cylinders... but will make it run extremely lumpy and/or high tickover

wayne

 

[ned]

Cheers man ill give it a try. Worse thing it started doing it just as my father in law took it for its MOT so instant fail on emission's. Dont suppose you could point me in right direction placement wise.