hi there i have a mk 3.5 fiesta with a frst engine running a t3. when its cold it runs fine but when warm it starts to miss and and kangeroo. this only happens when im doing a constant speed eg 30mph but stops if i put my foot down . ive tried spark plugs, leads, and other bits but no joy. any help would be appreciated thanx

 

i had the same thing on a corsa and it was the egr valve [exahaust gas recerculation valve] but im not sure if they have them on the erst worth checking out tho

 

no egr valves

does it do it only when hot?

id check fuelling. if of course no air leaks.