Hi all. I have a 2008 clio197 @51k it has recently developed a fault when i overtake or under heavy load it starts to shudder/missfire then clears and pulls ok. Iv read the codes but none stored! Tryed reading live data on missfire but nothing showing! Dose anyone have any ideas im thinking injector will be taking the plugs out to see what cylinder is missing via any black residue on the plug. Any help would be appreciated!!!