if its a coil which it probably is the overfueling may cause your cat to go .then you are into big money .leave it put as coils are not dear and you will only do more damage .most good motorfactors stock coils for renault and alot are open all weekend they are very easy to diagnose the faulty one.
remove the the plastic cover where your oil filler cap is cnd you will see 4 electrical plugs one per coil leave the engine running and disconnect each connector and see does the engine drop off when you come to the one which makes no difference to the tick over thats the one .all you need to remove it is a 10 mm socket .try this first and see does it make any difference if it does ring around a few motor factors they usually stock them