Originally Posted by Nash_mr2

head gasket blown between cylinders?

I had exactly the same symptoms on an old clio i had (sounding like it was running on 3) - changed the plugs, HT's, Coil, u name it i changed it! - still ran the same

someone suggested my Head gasket may have gone, i was like "Yeah, as if, am sure i'd know if that happend".......so i whipped the head off to find that the gasket had indeed split between the 2 middle cylinders so they were loosing compression between each other! stuck a new gasket on, job done!